The wolf of the wine ذِئْبُ الخَمَرِ

الخَمَر‏:‏ ما واراك من شجر أو حجر أو جرف وادٍ، وإنما يضاف إلى الخمر للزومه إياه، ومثله‏:‏ ذئب غَضاً، وقنفذ برقة، وتيس حلب، وهو نبت تعتادهُ الظباء، ويقال‏:‏ تيس الربل، وضب السحا، وشيطان الحَمَاطة، وأرنب الخلة‏.‏

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The proverb "a wolf in the thicket" is used to describesomeone who hides and lurks, waiting for an opportunity to pounce or cause harm, just as a wolf stays in thickets (i.e., dense vegetation or a concealed place) to ambush its prey.
The closest English proverbs and expressions that convey this meaning are:
A wolf in hiding.

Lurking in the shadows.

 lurking predator.
till waters run deep (in some contexts).
 wolf in sheep's clothing.
f the literal meaning of the Arabic proverb is intended, i.e., to lurk and lie in wait from a hidden place, then the best equivalent is:
"Lurking in the shadows like a wolf waiting for its prey." He lurks in the shadows like a wolf waiting for its prey
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For wine: that which conceals you from trees, stones, or the bank of a valley. It is added to wine because of its association with it. Similar to it are: a fresh wolf, a hedgehog of Barqa, and a goat of Aleppo, which is a plant that gazelles frequent. It is also said: the goat of the desert, the lizard of the Saha, the devil of the Hamata, and the rabbit of the Khillah.

A wolf entered upon you, a wolf. أخل إليك ذئب أزل

 The proverb "Ask yourself, you wolf" is used to warn a man. It means "Mind your own business." Al-Ja'di said:

"And that is one of the blows of death, so mind your own business and do not be surprised." The meaning of the proverb is: Mind your own business, for this is a wolf. It is used as a warning to a man. It is also narrated as "Ask yourself," meaning "Be alone." It is said, "I was alone," meaning I was alone and I left someone else alone. It can be transitive or intransitive. Ghani ibn Malik al-'Uqayli said: "I came to Layla with the young men, but I did not leave, so I was alone, and she became speechless in my solitude." His saying "to you" means "Mind your own business and your own affairs, for this is a wolf." "Azal" refers to someone who has no flesh on his thighs or hips, which makes him walk faster.

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 The closest English equivalent to this proverb is:

Look out — there’s a wolf about.

Meaning: Beware, danger is near.

Because the Arabic proverb contains a warning and alert to a swift and dangerous enemy, another close English equivalent is:

Keep your guard up.

Or:

Beware of a lean wolf.

This last one is very close to the original meaning, because the "lean wolf" is the lean, swift, and most dangerous wolf in its running and predation.

A similar proverb is:

Danger lurks nearby.

Meaning: Danger lurks near you, so be careful.

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يقال للرجل: أخل إليك. أي الزم شأنك. قال الجعدي:

وذلك من وقعات المنـو

ن فاخلي إليك ولا تعجبي

وتقدير المثل: الزم شأنك فهذا ذئب أزل. يضرب في التحذير للرجل. ويروى: أخل إليك، أي كن خالياً. يقال: أخليت، أي خلوت وأخليت غيري. يتعدى ولا يتعدى. قال غني بن مالك العقيلي:

أتيت مع الحداث ليلى فلم أبـن

فاخليت فاستعجمت عند خلائي

أي خلوت. وقوله: إليك، يريد أخل ضاما إليك أمرك وشأنك فإن هذا ذئب أزل. والأزل، الذي لا لحم على فخذيه ولا وركيه، وذلك أسرع له في المشي.