Criminal getting in under house (7)
I believe the answer is:
villain
'criminal' is the definition.
(both can mean a bad person)
'in under house' is the wordplay.
'under' is a charade indicator (letters next to each other) (below, in a down clue).
'house' becomes 'villa' (villa is a kind of house).
'in' put after 'villa' is 'VILLAIN'.
'getting' acts as a link.
(Other definitions for villain that I've seen before include "One played badly" , "Scoundrel" , "Wrongdoer" , "Criminal person" , "Criminal, rogue" .)