Wretched strikes I had backed (6)
I believe the answer is:
dismal
'wretched' is the definition.
(thesaurus)
'strikes i had backed' is the wordplay.
'strikes' becomes 'lams' (to lam means to hit hard).
'i had' becomes 'id' (I'd).
'backed' says the letters should be written in reverse.
'lams'+'id'='lamsid'
'lamsid' in reverse letter order is 'DISMAL'.
(Other definitions for dismal that I've seen before include "black and > blue" , "Very disappointing" , "describes economic science" , "Dull and dreary" , "Showing gloom, dreary" .)