One dweller turned out to be a layabout (4,2,4)
I believe the answer is:
neer do well
'a layabout' is the definition.
(ne'er-do-well is a kind of layabout)
'one dweller turned out' is the wordplay.
'turned out' indicates anagramming the letters (turn out can mean to organise).
'one'+'dweller'='onedweller'
'onedweller' anagrammed gives 'NEER-DO-WELL'.
'to be' is the link.
(Other definitions for neer do well that I've seen before include "Layabout" , "useless oaf" , "Black sheep" , "scallywag" , "Irresponsible person" .)