Food providing energy after journey (5)
I believe the answer is:
tripe
'food' is the definition.
(tripe is a kind of food)
'energy after journey' is the wordplay.
'energy' becomes 'e' (physics symbol as in E=mc2).
'after' says to put letters next to each other.
'journey' becomes 'trip' (trip is a kind of journey).
'e' put after 'trip' is 'TRIPE'.
'providing' acts as a link.
(Other definitions for tripe that I've seen before include "Rubbish, nonsense" , "Balderdash" , "load of rubbish?" , "Pants" , "Rot" .)