Strength enlivens pirouettes lacking in energy (7)
I believe the answer is:
stamina
'energy' is the definition.
(I've seen this before)
'strength enlivens pirouettes lacking in' is the wordplay.
I cannot quite understand how this works, but
'in' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for stamina that I've seen before include "capability to keep going" , "Endurance, strength to stay the course" , "Endurance - staying power" , "Sustained energy" , "Parts of flowers" .)