Grass snake possibly (5)

I believe the answer is:

sneak

'grass' is the definition.
(thesaurus)

'snake possibly' is the wordplay.
'possibly' is an anagram indicator.
'snake' with letters rearranged gives 'SNEAK'.

(Other definitions for sneak that I've seen before include "Go furtively and tell tales" , "thief" , "Underhanded tell-tale" , "Cringe" , "Creep" .)

I've seen this clue in the Evening Standard.

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