Hot line in forged notes (6)
I believe the answer is:
stolen
'hot' is the definition.
(thesaurus)
'line in forged notes' is the wordplay.
'line' becomes 'l'.
'in' is an insertion indicator.
'forged' indicates anagramming the letters.
'notes' is an anagram of 'stoen'.
'l' put into 'stoen' is 'STOLEN'.
(Other definitions for stolen that I've seen before include "Taken without permission or payment" , "Misappropriated; hot" , "Taken without the owner's consent" , "Pilfered" , "plagiarised?" .)