To put the cat back into the wager (4-2)
I believe the answer is:
toss-up
'the wager' is the definition.
(thesaurus)
'to put the cat back' is the wordplay.
'put' means one lot of letters go next to another.
'the cat' becomes 'puss' (puss is a kind of cat).
'back' shows that the letters should be reversed in order.
'puss' reversed gives 'ssup'.
'to'+'ssup'='TOSS-UP'
'into' is the link.
(Other definitions for toss-up that I've seen before include "Flip of a coin" , "Use of a coin to choose" , "Fifty-fifty chance" , "It helps you pick" .)