Idle fellow found under a lot of cargo (4)
I believe the answer is:
loaf
'idle' is the definition.
(loafing is a kind of idling)
'fellow found under a lot of cargo' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'found under' says to put letters next to each other.
'a lot of' means to remove the last letter (most of the word but not all of it).
'cargo' becomes 'load' ('load' can be a synonym of 'cargo').
'load' with its last letter taken off is 'loa'.
'f' after 'loa' is 'LOAF'.
(Other definitions for loaf that I've seen before include "Quantity of bread" , "cottage?" , "Bread unit" , "Piece of bread" , "Bread; loiter" .)