Singer has energy to shout (5)
I believe the answer is:
cheer
'to shout' is the definition.
(I've seen this before)
'singer has energy' is the wordplay.
'singer' becomes 'cher' (Cher is a US musician).
'has' indicates putting letters inside.
'energy' becomes 'e' (physics symbol as in E=mch).
'cher' enclosing 'e' is 'CHEER'.
(Other definitions for cheer that I've seen before include "Give comfort or support to" , "Encourage - applaud" , "Buck up" , "one in three, perhaps" , "Fare" .)