Intentionally lose the argument, saving energy (5)
I believe the answer is:
throw
'intentionally lose' is the definition.
(I've seen this in another clue)
'the argument saving energy' is the wordplay.
'argument' becomes 'row' (to row is to argue).
'saving' is a deletion indicator (saving can mean except).
'energy' becomes 'e' (physics symbol as in E=mc2).
'the'+'row'='therow'
'therow' with 'e' taken away is 'THROW'.
(Other definitions for throw that I've seen before include "Hurl; perplex" , "pitch or > floor" , "Discard" , "Dumbfound" , "put on floor" .)