Run away from end of the earth, returning with energy (5)
I believe the answer is:
elope
'run away from' is the definition.
(thesaurus)
'end of the earth returning with energy' is the wordplay.
'end of the earth' becomes 'pole' (I've seen this in another clue).
'returning' is a reversal indicator.
'with' means one lot of letters go next to another.
'energy' becomes 'e' (physics symbol as in E=mc2).
'pole' written backwards gives 'elop'.
'elop'+'e'='ELOPE'
(Other definitions for elope that I've seen before include "Run away to Gretna Green?" , "do a moonlight flit" , "Abscond for amorous purposes" , "go off to the match?" , "run off with another?" .)