Jammed cylinder (5,4)
I believe the answer is:
swiss roll
'jammed cylinder' is the definition.
(jammed meaning with jam in it)
'jammed cylinder' is the wordplay.
'jammed' becomes 'swiss' (I can't justify this - if you can you should give a lot more credence to this answer).
'cylinder' becomes 'roll' (roll is a kind of cylinder).
'swiss'+'roll'='SWISS ROLL'
Can you help me to learn more?
(Other definitions for swiss roll that I've seen before include "teatime treat?" , "Tumble down the ski slopes maybe" , "Filled sponge cake" , "Type of sponge cake" , "Cylindrical sponge cake with layers of jam" .)