Cleaners win lottery (10)
I believe the answer is:
sweepstake
'lottery' is the definition.
(sweepstake is a kind of lottery)
'cleaners win' is the wordplay.
'cleaners' becomes 'sweeps' (sweep is a kind of cleaner).
'win' becomes 'take' (taking is a kind of winning).
'sweeps'+'take'='SWEEPSTAKE'
(Other definitions for sweepstake that I've seen before include "System of gambling, especially on horse races" , "action on race" , "prize" , "I'd bet on it" , "Lottery" .)