Ending on benefit, request job (4)
I believe the answer is:
task
'job' is the definition.
(synonyms)
'ending on benefit request' is the wordplay.
'ending on' suggests the final letters.
'request' becomes 'ask' (synonyms).
The last letter of 'benefit' is 't'.
't'+'ask'='TASK'
(Other definitions for task that I've seen before include "Difficult piece of work" , "Allocate work" , "commission" , "Arduous bit of work" , "Assignment" .)