Dash to confess about affair (10)
I believe the answer is:
smattering
'dash' is the definition.
(thesaurus)
'confess about affair' is the wordplay.
'confess' becomes 'sing' (I've seen this before).
'about' is an insertion indicator.
'affair' becomes 'matter' ('matter' can be a synonym of 'affair'**).
'sing' placed around 'matter' is 'SMATTERING'.
'to' acts as a link.
(Other definitions for smattering that I've seen before include "Hint" , "superficial knowledge" , "Little bit" , "Tiny amount (of knowledge)" , "Taste" .)