Replay’s beginning at ten or five to three, perhaps (5)
I believe the answer is:
ratio
'five to three perhaps' is the definition.
(five to three is a ratio)
'replay's beginning at ten' is the wordplay.
'beginning' indicates taking the first letters.
'ten' becomes 'IO' (IO resembles 10).
The first letter of 'replays' is 'r'.
'r'+'at'+'io'='RATIO'
'or' acts as a link.
(Other definitions for ratio that I've seen before include "3 relation" , "Relationship found in a riot" , "Percentage" , "nine-to-five, say" , "Eg, 4 to 3" .)