Energy of cover version (5)
I believe the answer is:
verve
'energy' is the definition.
(verve is a kind of energy)
'of cover version' is the wordplay.
'of' indicates the answer is hidden within the clue.
'VERVE' can be found hidden inside 'cover version'.
(Other definitions for verve that I've seen before include "Root tasting of oysters" , "Energy and zest" , "Great liveliness or enthusiasm" , "Vigour, spirit, style" , "Zest and exuberance" .)