Hazy old boys find antidote (7)
I believe the answer is:
obscure
'hazy' is the definition.
(thesaurus)
'old boys find antidote' is the wordplay.
'old boys' becomes 'OBs' (OB is short for old boy).
'find' is a charade indicator (letters next to each other).
'antidote' becomes 'cure' (I've seen this in another clue).
'obs'+'cure'='OBSCURE'
(Other definitions for obscure that I've seen before include "Not distinct" , "Recondite, abstruse" , "Little-known" , "Dim, vague or not well known" , "unimportant" .)