People endlessly swallowing one's scotch (4)
I believe the answer is:
foil
'scotch' is the definition.
(I know that scotch can be written as foil)
'people endlessly swallowing one's' is the wordplay.
'people' becomes 'folk' (informal term for people).
'endlessly' means to remove the last letter.
'swallowing' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'folk' with its last letter taken away is 'fol'.
'fol' enclosing 'i' is 'FOIL'.
(Other definitions for foil that I've seen before include "Piece of thin and flexible sheet metal" , "Repulse" , "Fencing rapier" , "Baffle" , "blunt weapon" .)