Note's money, reportedly (3)
I believe the answer is:
doh
'note's' is the definition.
(alternative spelling of 'do' as in do re mi)
'money reportedly' is the wordplay.
'money' becomes 'dough' (dough is a kind of money).
'reportedly' shows a homophone (sound like).
'dough' is a homophone of 'DOH'.
(Other definitions for doh that I've seen before include "First and eighth note in tonic sol-fa" , "an exclamation from someone who's annoyed with himself" , "First note of musical scale" , "How foolish of me" , "First note of major scale in music" .)