Would do well, in short, to work for a fee with returning representatives (7)
I believe the answer is:
prosper
'would do well in short' is the definition.
I can't judge whether this defines the answer.
'work for a fee with returning representatives' is the wordplay.
'work for a fee' becomes 'pro' (I can't explain this - if you can you should give a lot more credence to this answer).
'with' means one lot of letters go next to another.
'returning' says the letters should be written in reverse.
'representatives' becomes 'reps' (rep is a kind of representative).
'reps' reversed gives 'sper'.
'pro'+'sper'='PROSPER'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for prosper that I've seen before include "Make good" , "Succeed, flourish" , "like Merimee, nominally" , "Go well" , "Get rich" .)