Collusion wasted cash, too (7)
I believe the answer is:
cahoots
'collusion' is the definition.
(to be 'in cahoots' is to collude with someone)
'wasted cash too' is the wordplay.
'wasted' indicates an anagram.
'cash'+'too'='cashtoo'
'cashtoo' with letters rearranged gives 'CAHOOTS'.
(Other definitions for cahoots that I've seen before include "In - means colluding" , "Collusion" , "In such agreement" , "League" , "(In) conspiracy" .)