Smashed gun having incurred fine (6)
I believe the answer is:
broken
'smashed' is the definition.
(similar in meaning)
'gun having incurred fine' is the wordplay.
'gun' becomes 'bren' (Bren is an example).
'having incurred' means one lot of letters goes inside another (incur can mean to collect).
'fine' becomes 'ok' (synonyms).
'bren' going around 'ok' is 'BROKEN'.
(Other definitions for broken that I've seen before include "If it's not ..., don't fix it" , "Shattered, perhaps emotionally" , "Interrupted; smashed" , "Damaged, in need of repair" , "Defective" .)