Tricky situation when energy's lacking in fight (5)
I believe the answer is:
scrap
'fight' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
(Other definitions for scrap that I've seen before include "Ditch - fight" , "Informal fight for waste material" , "Discard; a bit" , "row" , "Discarded material" .)