Hot line in forged notes (6)
I believe the answer is:
Here is my best explanation:
'hot' is the definition.
'line in forged notes' is the subsidiary indication.
'line' becomes 'l'.
'in' indicates putting letters inside.
'forged' indicates an anagram.
'notes' with letters rearranged gives 'stoen'.
'l' put inside 'stoen' is 'stolen'.
(Other definitions for stolen that I've seen before include "Taken without permission or payment", "Hot", "Taken without the owner's consent", "Purloined or embezzled", "Nicked", "Filched", "Taken dishonestly", "Robbed", "Lifted" and "Pilfered".)