Gladys is a woman of refinement at heart (4)
I believe the answer is:
lady
'heart' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'gladys is a woman of refinement' is the wordplay.
'LADY' is hidden in amongst the letters.
However, I'm not sure how the hidden word is indicated.
'at' is the link.
Can you help me to learn more?
(Other definitions for lady that I've seen before include "Gentlewoman" , "mature woman" , "Title for a knight's wife" , "older female" , "Lord's wife - peeress's title" .)