After whiskey, John spins yarn (4)
I believe the answer is:
wool
'yarn' is the definition.
(I've seen this before)
'after whiskey john spins' is the wordplay.
'after' is a charade indicator (letters next to each other).
'whiskey' becomes 'w' (alpha bravo charlie delta ...).
'john' becomes 'loo' (loo is a kind of john).
'spins' says the letters should be written in reverse (I've seen 'spin' mean this).
'loo' backwards is 'ool'.
'w' next to 'ool' is 'WOOL'.
(Other definitions for wool that I've seen before include "Sheep's coat" , "Fabric made from animal hair" , "Sheep's fleece" , "Sheep's hair" , "Ovine product" .)