Girl, ten, let loose curl (7)
I believe the answer is:
ringlet
'curl' is the definition.
(I know that curl can be written as ringlet)
'girl ten let loose' is the wordplay.
'let loose' indicates an anagram.
'girl'+'ten'='girlten'
'girlten' anagrammed gives 'RINGLET'.
(Other definitions for ringlet that I've seen before include "Hair curl, of an Irish dancer perhaps" , "A long tubular curl" , "Curled lock of hair" , "Long curl of hair" , "twist of sorts?" .)