Money to make; not nice (5)
I believe the answer is:
dough
'money' is the definition.
(dough can informally mean money)
'make not nice' is the wordplay.
'make' becomes 'do' (do can mean to make or prepare).
'not nice' becomes 'ugh' (I can't explain this - if you can you should believe this answer much more).
'do'+'ugh'='DOUGH'
'to' is the link.
Can you help me to learn more?
(Other definitions for dough that I've seen before include "Floury mixture" , "Stiff flour mixture" , "Flour mixture for bread and pastry" , "Moistened flour" , "Money (slang)" .)