Repeatedly making a profit (5)
I believe the answer is:
again
'repeatedly' is the definition.
(I've seen this before)
'a profit' is the wordplay.
'profit' becomes 'gain' (synonyms).
'a'+'gain'='AGAIN'
'making' is the link.
(Other definitions for again that I've seen before include "Anew" , "Here we go ___" , "'Another time, once more (5)'" , "Predictably perhaps" , "Next time" .)