Jargon or tag that is misquoted (5)
I believe the answer is:
argot
'jargon' is the definition.
(argot can mean jargon or slang)
'or tag that is misquoted' is the wordplay.
'that is misquoted' indicates anagramming the letters (an inaccurate or mistaken spelling).
'or'+'tag'='ortag'
'ortag' is an anagram of 'ARGOT'.
(Other definitions for argot that I've seen before include "Cant" , "Talk of thieves" , "Groat (anag)" , "Criminal jargon" , "Special language of a groat?" .)