Father gets energy from pontiff (4)
I believe the answer is:
pope
'pontiff' is the definition.
(I know that pontiff can be written as pope)
'father gets energy' is the wordplay.
'father' becomes 'pop' (pop is a kind of father).
'gets' means one lot of letters go next to another.
'energy' becomes 'e' (physics symbol as in E=mco).
'pop'+'e'='POPE'
'from' acts as a link.
(Other definitions for pope that I've seen before include "fisherman's successor" , "Catholic leader" , "Well-versed man" , "church leader in Rome" , "served in the Vatican" .)