Pulse of a bit of bubble gum, essentially (6)
I believe the answer is:
legume
'pulse' is the definition.
(I've seen this before)
'a bit of bubble gum essentially' is the wordplay.
'a bit of' indicates a hidden word.
'LEGUME' is hidden in the letters of 'bubble gum essentially'.
'of' is the link.
(Other definitions for legume that I've seen before include "A fruit that bears its seed in pods" , "Bean, pea etc" , "Glue me (anag) - climbing bean or pea plant" , "Crop plant of pea family" , "pulse" .)