Jam infused with drop of rum is a sensation (7)
I believe the answer is:
prickle
'sensation' is the definition.
(I have seen 'Stinging sensation ' mean 'prickle' so perhaps 'sensation' could also mean 'prickle')
'jam infused with drop of rum' is the wordplay.
'jam' becomes 'pickle' (synonyms).
'infused with' indicates putting letters inside.
'drop of rum' becomes 'r' (I can't justify this - if you can you should give a lot more credence to this answer).
'pickle' enclosing 'r' is 'PRICKLE'.
'is a' acts as a link.
Can you help me to learn more?
(Other definitions for prickle that I've seen before include "sharp point" , "Part of a burr or a hedgehog" , "Stinging sensation" , "Short spine" , "Spine, thorn" .)