Train with energy and weapon (5)
I believe the answer is:
spear
'weapon' is the definition.
(spear is a kind of weapon)
'train with energy' is the wordplay.
'train' becomes 'sar' (I can't justify this - if you can you should give a lot more credence to this answer).
'with' indicates putting letters inside.
'energy' becomes 'P.E.' (P.E. is an example).
'sar' placed around 'pe' is 'SPEAR'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for spear that I've seen before include "pierce with this?" , "Asparagus shoot" , "Thrown weapon" , "Impale" , "Sharp-tipped weapon" .)