An approving gesture about girl (5)
I believe the answer is:
donna
'girl' is the definition.
'an approving gesture about' is the wordplay.
'approving gesture' becomes 'nod' (gesture which indicates approval).
'about' says the letters should be written backwards.
'an'+'nod'='annod'
'annod' back-to-front is 'DONNA'.
(Other definitions for donna that I've seen before include "Girl" , "Italian woman of rank" , "See 10" , "Spanish lady's title" , "Female" .)