"National Velvet" author Bagnold (4)
I believe the answer is:
enid
'national velvet author bagnold' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for enid that I've seen before include "Geraint's wife's" , "Geraint's loved one" , "Dine with Ms blyton, writer" , "Lady" , "W - - Blyton" .)