Strike legislation rejected -- left work (6)
I believe the answer is:
wallop
'strike' is the definition.
(thesaurus)
'legislation rejected left work' is the wordplay.
'legislation' becomes 'law' (I've seen this before).
'rejected' says the letters should be written in reverse.
'left' becomes 'l' (common abbreviation).
'work' becomes 'op' (abbreviation for opus).
'law' reversed gives 'wal'.
'wal'+'l'+'op'='WALLOP'
(Other definitions for wallop that I've seen before include "batter" , "big hit" , "A heavy resounding blow (6)" , "Alcoholic drink" , "Punch" .)