Untidy guy's given name (6)
I believe the answer is:
ragtag
'untidy' is the definition.
(ragtag can mean untidy or disordered)
'guy's given name' is the wordplay.
'guy' becomes 'rag' (both can mean to tease or mock).
'given' says to put letters next to each other.
'name' becomes 'tag' (I've seen this in other clues).
'rag'+'tag'='RAGTAG'
(Other definitions for ragtag that I've seen before include "Scruffy" , "Incongruously varied in character" , "Mob" , "Masses" , "Disorderly" .)