Fast time over, then slow (5)
I believe the answer is:
lento
'slow' is the definition.
(similar in meaning)
'fast time over' is the wordplay.
'fast time' becomes 'lent' (a period of fasting).
'over' becomes 'o' (cricket abbreviation).
'lent'+'o'='LENTO'
'then' acts as a link.
(Other definitions for lento that I've seen before include "Slowly (mus.)" , "Slow (mus.)" , "How one scores slowly" , "Slow (music)" , "It's slower than adagio" .)