Bar providing energy (sustained energy), almost other-worldly (9)
I believe the answer is:
estaminet
'bar' is the definition.
(I have seen 'small bar' mean 'estaminet' so perhaps 'bar' could also mean 'estaminet')
'energy sustained energy almost other-worldly' is the wordplay.
'energy' becomes 'e' (physics symbol as in E=mc2).
'sustained energy' becomes 'stamina' (I've seen this before).
'almost' means to remove the last letter (most of the word but not all of it).
'other-worldly' becomes 'et' (abbreviation for extra-terrestrial).
'stamina' with its last letter taken off is 'stamin'.
'e'+'stamin'+'et'='ESTAMINET'
'providing' is the link.
(Other definitions for estaminet that I've seen before include "provides food and drink" , "Neat items (anag) - small bar or cafe" , "Small French cafe" , "French restaurant" , "eatery" .)