Cheat to write about pinching millions (3-5)
I believe the answer is:
two-timer
'cheat' is the definition.
(I know that two-timer is a type of cheat)
'to write about pinching millions' is the wordplay.
'about' indicates an anagram.
'pinching' indicates putting letters inside (taking inside).
'millions' becomes 'm' (abbreviation).
'to'+'write'='towrite'
'towrite' with letters rearranged gives 'twotier'.
'twotier' placed around 'm' is 'TWO-TIMER'.
(Other definitions for two-timer that I've seen before include "Deceiver" , "Double-crosser" , "One sleeps around" , "Unfaithful person" , "Unfaithful partner" .)