Musical act in Barnet (6)
I believe the answer is:
hairdo
'barnet' is the definition.
(I've seen this before)
'musical act' is the wordplay.
'musical' becomes 'hair' (I've seen this before).
'act' becomes 'do' (I've seen this in other clues).
'hair'+'do'='HAIRDO'
'in' is the link.
(Other definitions for hairdo that I've seen before include "Style for one's crowning glory" , "Say, crew cut" , "Bob, perm or bouffant" , "Arrangement of locks" , "capital arrangement" .)