Dispense with amateur tax returns (5)
I believe the answer is:
allot
'dispense' is the definition.
(allotting is a kind of dispensing)
'with amateur tax returns' is the wordplay.
'with' says to put letters next to each other.
'amateur' becomes 'a'.
'tax' becomes 'toll' (I've seen this in other clues**).
'returns' says the letters should be written backwards.
'toll' backwards is 'llot'.
'a' put next to 'llot' is 'ALLOT'.
(Other definitions for allot that I've seen before include "Award (share, task)" , "split up" , "Ration" , "Designate; sounds like much" , "Allocate" .)