Exaggerate extra tip-off fact (7)
I believe the answer is:
overact
'exaggerate' is the definition.
(I've seen this before)
'extra tip-off fact' is the wordplay.
'extra' becomes 'over' (both can mean left over).
'tip-off' means to remove the first letter (one tip of the word is removed).
'fact' with its initial letter taken away is 'act'.
'over'+'act'='OVERACT'
(Other definitions for overact that I've seen before include "behave exaggeratedly" , "Play role exaggeratedly" , "Be unsubtle on stage" , "In part, fail to convince" , "Cartoon twenty four across" .)