Fixed payment sees writers hit back (7)
I believe the answer is:
pension
'fixed payment' is the definition.
'pension' can be an answer for 'payment' (pension is a kind of payment). I am not certain of the 'fixed' bit.
'writers hit back' is the wordplay.
'writers' becomes 'pens' (writing implements).
'hit back' becomes 'ion' (I can't explain this - if you can you should give a lot more credence to this answer).
'pens'+'ion'='PENSION'
'sees' acts as a link.
Can you help me to learn more?
(Other definitions for pension that I've seen before include "support for the elderly" , "Payment to traitor" , "what oldies may have earned" , "Payment to retired persons a continental boarding house" , "Nice little hotel" .)