He fights, but not for money (9)
I believe the answer is:
contender
'he fights' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'not for money' is the wordplay.
'not' becomes 'con' (I've seen this in other clues).
'for' means one lot of letters go next to another.
'money' becomes 'tender' (I've seen this in another clue).
'con'+'tender'='CONTENDER'
'but' is the link.
Can you help me to learn more?
(Other definitions for contender that I've seen before include "One struggling" , "Trend once (anag.)" , "One striving" , "One engaged in a struggle" , "one in the field" .)