Gladstone carrying much weight (3)
I believe the answer is:
ton
'much weight' is the definition.
(unit of weight)
'gladstone carrying' is the wordplay.
'carrying' indicates a hidden word.
'TON' is hidden in the letters of 'gladstone'.
(Other definitions for ton that I've seen before include "20 cwt" , "20cwt" , "Unit of weight equivalent to 2240 pounds" , "Style" , "People of fashion" .)