Dumas character who sat untidily around the house (5)
I believe the answer is:
athos
'dumas character' is the definition.
(I've seen this in another clue)
'sat untidily around the house' is the wordplay.
'untidily' indicates anagramming the letters (I've seen this in other clues).
'around' is an insertion indicator.
'the house' becomes 'ho' (abbreviation for house).
'sat' anagrammed gives 'ats'.
'ats' enclosing 'ho' is 'ATHOS'.
'who' acts as a link.
(Other definitions for athos that I've seen before include "Greek monastic mountain" , "Greek mountain; one of the three musketeers" , "Greece's holy mount" , "Literary musketeer" , "Dumas musketeer" .)