Deliberately lose argument following hollow triumph (5)
I believe the answer is:
throw
'deliberately lose' is the definition.
(I've seen this before)
'argument following hollow triumph' is the wordplay.
'argument' becomes 'row' (to row is to argue).
'following' means one lot of letters go next to another.
'hollow' means to remove the middle letters (the word is hollowed out).
'triumph' with its middle taken out is 'th'.
'row' after 'th' is 'THROW'.
(Other definitions for throw that I've seen before include "Discard" , "Project through the air" , "blanket" , "Chuck - confuse" , "Form (pot) on a wheel" .)