Firm close to being smashed (5)
I believe the answer is:
tight
I believe this clue is a triple definition!
'firm' is the first definition.
(synonyms)
'close' is the second definition.
(synonyms)
'to being smashed' is the third definition.
(synonyms)
(Other definitions for tight that I've seen before include "Drunk - a near thing!" , "Drunk; giving little room" , "Hard to move; drunk" , "Miserly (informal) - drunk (informal)" , "corked?" .)