Box only initially missing from humorous drawing (6)
I believe the answer is:
carton
'box' is the definition.
(I know that carton is a type of box)
'missing from humorous drawing' is the wordplay.
'missing' is a deletion indicator.
'from' becomes 'o' (I've seen this in other clues).
'humorous drawing' becomes 'cartoon' (I've seen this before).
'cartoon' with 'o' taken away is 'CARTON'.
'only initially' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
(Other definitions for carton that I've seen before include "Light cardboard box" , "Box made of cardboard" , "He did a far, far better thing" , "Box without great strength" , "Dickensian hero" .)