Supplied to a G man? (3)
I believe the answer is:
fed
This clue is a double definition.
'supplied' is the first definition.
(feeding is a kind of supplying)
'a g man?' is the second definition.
(thesaurus)
'to' acts as a link.
(Other definitions for fed that I've seen before include "Given sustenance" , "Given food to eat" , "Nourished" , "Provided food for" , "Banking authority" .)