Ready to cheat mum (4)
I believe the answer is:
dosh
'ready' is the definition.
(I've seen this before)
'cheat mum' is the wordplay.
'cheat' becomes 'do'.
'mum' becomes 'sh' (both can mean to be quiet).
'do'+'sh'='DOSH'
'to' is the link.
(Other definitions for dosh that I've seen before include "Money (sl.)" , "Lolly (slang)" , "cash" , "Moolah (slang)" , "currency" .)