I caught ball (3)
I believe the answer is:
eye
'ball' is the definition.
(eyeball)
'i caught' is the wordplay.
'caught' shows a homophone (sound like) (to catch something can mean to hear it).
'i' is a homophone of 'EYE'.
(Other definitions for eye that I've seen before include "Organ of vision" , "Watch - middle of cyclone" , "Bit of a potato (or a needle?)" , "'Cast a cold ... on life, on death' (Yeats)" , "Aim for" .)