Goes round yelling at first, claiming I’m filthy ... (5)
I believe the answer is:
grimy
'filthy' is the definition.
(I've seen this before)
'goes round yelling at first claiming i'm' is the wordplay.
'at first' suggests taking the first letters.
'claiming' indicates putting letters inside.
The initial letters of 'goes round yelling' is 'gry'.
'gry' going around 'im' is 'GRIMY'.
(Other definitions for grimy that I've seen before include "Dirty - soiled" , "Besmirched" , "grunge" , "smutty" , "Mucky" .)