Energy head tours university (6)
I believe the answer is:
bounce
'energy' is the definition.
(bounce can mean energy or liveliness)
'head tours university' is the wordplay.
'head' becomes 'bonce' (informal term for a person's head).
'tours' indicates putting letters inside (to tour can mean to go around).
'university' becomes 'u' (abbreviation for university).
'bonce' going around 'u' is 'BOUNCE'.
(Other definitions for bounce that I've seen before include "Reflect back from a surface" , "Move energetically; rebound" , "Rebound (like a cheque)" , "Spring back like a rubber ball" , "Spring back; resilience" .)