Knight under scarf is hot (6)
I believe the answer is:
stolen
'hot' is the definition.
(thesaurus)
'knight under scarf' is the wordplay.
'knight' becomes 'n' (chess).
'under' means one lot of letters go next to another.
'scarf' becomes 'stole' (stole is a kind of scarf).
'n' put after 'stole' is 'STOLEN'.
'is' acts as a link.
(Other definitions for stolen that I've seen before include "Nicked" , "Taken without the owner's consent" , "Taken without permission or payment" , "without keeping to left" , "Purloined in Solent" .)