Awfully inane girl (5)
I believe the answer is:
annie
'girl' is the definition.
'awfully inane' is the wordplay.
'awfully' indicates an anagram.
'inane' with letters rearranged gives 'ANNIE'.
(Other definitions for annie that I've seen before include "-- Laurie, Scots song" , "Musical inspired by comic strip" , "Miss Laurie" , "said to carry a gun" , "-- Oakley (Wild West)" .)