Stupidly wrecks car! Wife goes bonkers (8)
I believe the answer is:
crackers
'bonkers' is the definition.
(synonyms)
'stupidly wrecks car wife goes' is the wordplay.
'stupidly' is an anagram indicator.
'wife' becomes 'w'.
'goes' is a deletion indicator.
'wrecks'+'car'='wreckscar'
'wreckscar' with 'w' removed is 'reckscar'.
'reckscar' anagrammed gives 'CRACKERS'.
(Other definitions for crackers that I've seen before include "Crazy - (American) biscuits" , "Round the bend" , "they may be on the table at Christmas" , "full of bad jokes at Yuletide?" , "Biscuits; fireworks" .)