Back as employment for banger (7)
I believe the answer is:
sausage
'banger' is the definition.
(I've seen this before)
'back as employment' is the wordplay.
'back' says the letters should be written backwards.
'employment' becomes 'usage' (synonyms).
'as' back-to-front is 'sa'.
'sa'+'usage'='SAUSAGE'
'for' is the link.
(Other definitions for sausage that I've seen before include "Eg, salami or pepperoni" , "Minced meat and fat in cylindrical skin" , "Long, bagged meat product" , "sort of roll?" , "Assuage (anag.)" .)