Best way after argument is rejected (5)
I believe the answer is:
worst
'best' is the definition.
(thesaurus)
'way after argument is rejected' is the wordplay.
'way' becomes 'st' (**).
'after' says to put letters next to each other.
'argument' becomes 'row' (I've seen this before).
'is rejected' says the letters should be written backwards.
'row' in reverse letter order is 'wor'.
'st' put after 'wor' is 'WORST'.
(Other definitions for worst that I've seen before include "Most badly" , "the pits" , "Most severe" , "Lowest of the low" , "Strangely, best" .)