Carrying the large one is too much for him (6)
I believe the answer is:
oliver
'him' is the definition.
'carrying the large one is too much' is the wordplay.
'carrying' indicates putting letters inside.
'the large' becomes 'L' (eg in clothes sizes).
'one' becomes 'i' (Roman numeral).
'is too much' becomes 'over' (over can mean to too great an extent).
'l'+'i'='li'
'li' going within 'over' is 'OLIVER'.
'for' acts as a link.
(Other definitions for oliver that I've seen before include "Dickens-based musical" , "Musical from Dickens novel" , "Musical based on the story of Dickens boy" , "stage show" , "-- Reed, actor" .)