Brat to con quietly (5)
I believe the answer is:
scamp
'brat' is the definition.
(I've seen this in another clue)
'con quietly' is the wordplay.
'con' becomes 'scam' (both can mean a fraudulent scheme).
'quietly' becomes 'p' (musical symbol).
'scam'+'p'='SCAMP'
'to' is the link.
(Other definitions for scamp that I've seen before include "Tearaway" , "Impish child" , "Rogue - perform inadequately" , "villain" , "Scoundrel" .)