Gladstone's son (3)
I believe the answer is:
'son' is the definition.
(lad can mean a boy or son)
'gladstone's' is the wordplay.
'LAD' is hidden in amongst the letters.
But, I am uncertain how this is indicated.
Can you help me to learn more?
(Other definitions for lad that I've seen before include "Stable employee" , "Son" , "Boy, familiar" , "(Housman's Shropshire) boy" , "Boy or youth" .)