Rotten crack in ball (3,5)
I believe the answer is:
off break
'ball' is the definition.
(I've seen this before)
'rotten crack' is the wordplay.
'rotten' becomes 'off' (rotten food is 'off').
'crack' becomes 'break'.
'off'+'break'='OFF-BREAK'
'in' acts as a link.
(Other definitions for off break that I've seen before include "Ball" , "One result of bowling" , "Spinner's delivery" .)