Lock phone, given licence (7)
I believe the answer is:
ringlet
'lock' is the definition.
(both can mean a piece of someone's hair)
'phone given licence' is the wordplay.
'phone' becomes 'ring' (synonyms).
'given licence' becomes 'let' (to give licence is to let someone do something).
'ring'+'let'='RINGLET'
(Other definitions for ringlet that I've seen before include "hair styling" , "Hair curl, of an Irish dancer perhaps" , "Curled lock of hair" , "Curling lock of hair" , "A curl - kind of tingler" .)