How the ballboy gets when he puts on weight? (7)
I believe the answer is:
rounder
'how the ballboy gets' is the definition.
I can't judge whether this definition defines the answer.
'he puts on weight?' is the wordplay.
I cannot really understand how this works, but
'he' could be 'der' and 'der' is found in the answer.
This explanation may well be incorrect...
'when' acts as a link.
Can you help me to learn more?
(Other definitions for rounder that I've seen before include "More circular" , "complete circuit in a game" , "More spherical" , "More rotund" , "Or under (anag.)" .)