Elevated argument over this is lacking value (5)
I believe the answer is:
worth
'value' is the definition.
(thesaurus)
'elevated argument over this is lacking' is the wordplay.
'elevated' shows that the letters should be reversed in order.
'argument' becomes 'row' (I've seen this before).
'over' means one lot of letters go next to another.
'lacking' suggests deleting specific letters.
'row' written backwards gives 'wor'.
'this' with 'is' taken away is 'th'.
'wor'+'th'='WORTH'
(Other definitions for worth that I've seen before include "Value (of something)" , "Merit - value" , "Throw (anag.)" .)