Criminal covers same ground in cellar (8)
I believe the answer is:
basement
'cellar' is the definition.
(synonyms)
'criminal covers same ground' is the wordplay.
'criminal' becomes 'bent' (bent can mean corrupt or criminal).
'covers' means one lot of letters goes inside another.
'ground' indicates anagramming the letters ('grind' the letters into a new form).
'same' is an anagram of 'asem'.
'bent' going around 'asem' is 'BASEMENT'.
'in' acts as a link.
(Other definitions for basement that I've seen before include "space below stairs" , "Beats men up in cellar" , "low point" , "Part of house below ground" , "Man beset in bottom of house" .)