About to dance around with energy and rhythm (7)
I believe the answer is:
cadence
'rhythm' is the definition.
(cadence is a kind of rhythm)
'about to dance around with energy' is the wordplay.
'about' becomes 'c' (abbreviation for circa).
'to' is a charade indicator (letters next to each other).
'around with' indicates an anagram.
'energy' becomes 'e' (physics symbol as in E=mc2).
'dance' anagrammed with 'e' makes 'adence'.
'c'+'adence'='CADENCE'
'and' is the link.
(Other definitions for cadence that I've seen before include "Modulation of the voice" , "Inflection; voice pitch fall" , "Close of a musical phrase" , "Vocal modulation or inflection" , "Rhythm or beat" .)