Partner no longer works to raise bonus (5)
I believe the answer is:
extra
'bonus' is the definition.
(I've seen this in another clue)
'partner no longer works to raise' is the wordplay.
'partner no longer' becomes 'ex' (I've seen this in other clues).
'works' becomes 'art' (I've seen this before).
'to raise' says the letters should be written backwards (in a down clue, letters go up).
'art' written backwards gives 'tra'.
'ex'+'tra'='EXTRA'
(Other definitions for extra that I've seen before include "Ancillary" , "Minor person screened" , "lesser player" , "Additional - bye" , "One playing small part" .)