On the other hand, it is a profit (5)
I believe the answer is:
again
'on the other hand' is the definition.
(I've seen this before)
'a profit' is the wordplay.
'profit' becomes 'gain' (synonyms).
'a'+'gain'='AGAIN'
'it is' is the link.
(Other definitions for again that I've seen before include "Ocne more" , "Repeatedly" , "Anew" , "Predictably perhaps" , "Moreover - a second time" .)