Can move in free and that’s bad (6)
I believe the answer is:
rancid
'bad' is the definition.
(I've seen this in another clue)
'can move in free' is the wordplay.
'move' indicates anagramming the letters.
'in' indicates putting letters inside.
'free' becomes 'rid' (to be free of something is to be rid of it).
'can' anagrammed gives 'anc'.
'anc' going inside 'rid' is 'RANCID'.
'and that's' is the link.
(Other definitions for rancid that I've seen before include "Stale, rank" , "Sour like stale grease 96)" , "Fetid" , "No longer fresh" , "Sour like stale fat" .)