Stress it's money on account (6)
I believe the answer is:
accent
'stress' is the definition.
(accent can mean to emphasise or stress)
'money on account' is the wordplay.
'money' becomes 'cent' (eg denomination of dollars).
'on' is a charade indicator (letters next to each other).
'account' becomes 'ac' (abbreviation for account).
'cent' put after 'ac' is 'ACCENT'.
'it's' is the link.
(Other definitions for accent that I've seen before include "Mark used to indecate pronunciation" , "Possibly a grave sign" , "Place stress on, say a syllable" , "Emphasis; mark on a letter" , "Distinctive way fo speaking" .)