Cheese mostly served with nothing to provide energy (4)
I believe the answer is:
brio
'energy' is the definition.
(brio is a musical term meaning energy)
'cheese mostly served with nothing' is the wordplay.
'cheese' becomes 'Brie' (Brie is an example).
'mostly' means to remove the last letter.
'served with' means one lot of letters go next to another.
'nothing' becomes 'O' (looks like zero - 0).
'brie' with its last letter taken away is 'bri'.
'bri'+'o'='BRIO'
'to provide' is the link.
(Other definitions for brio that I've seen before include "Sparkle" , "Dash or verve, from Italian" , "'Con ..., musically with vigour (4)'" , "'Liveliness, vivacity (4)'" , "Spiritedness" .)