Make a profit once more (5)
I believe the answer is:
again
'once more' is the definition.
(synonyms)
'make a profit' is the wordplay.
I cannot really understand how this works, but
'make' could be 'gain' (synonyms) and 'gain' is present in the answer.
'a' is present in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for again that I've seen before include "Next time" , "second term" , "Furthermore" , "Moreover - a second time" , "'Another time, once more (5)'" .)