Gladstone’s boy (3)
I believe the answer is:
lad
'boy' is the definition.
(informal term for boy)
'gladstone's' is the wordplay.
'LAD' is hidden within the letters.
But, I am not sure how the hidden word is indicated.
Can you help me to learn more?
(Other definitions for lad that I've seen before include "Chap, fellow" , "A young chap into ballads" , "Stable employee" , "Boy, young man" , "(Housman's Shropshire) boy" .)