Signify average male has energy (4)
I believe the answer is:
mean
'signify' is the definition.
(synonyms)
'average male has energy' is the wordplay.
'average male' becomes 'man' (man is a kind of male. I am not sure about the 'average' bit.).
'has' indicates putting letters inside.
'energy' becomes 'e' (physics symbol as in E=mca).
'man' enclosing 'e' is 'MEAN'.
Can you help me to learn more?
(Other definitions for mean that I've seen before include "spell" , "mercenary" , "Intend; stingy" , "Signify; miserly" , "Represent - average" .)