Adult female (5)
I believe the answer is:
woman
'adult female' is the definition.
(I know that adult female can be written as woman)
This is all the clue.
(Other definitions for woman that I've seen before include "Lady" , "See 16" , "Mature female" , "With 1a [OLD], one's rather timid" , "person not going on stag-night" .)