Principled one coming in shabby chalet (7)
I believe the answer is:
ethical
'principled' is the definition.
(I've seen this before)
'one coming in shabby chalet' is the wordplay.
'one' becomes 'I' (Roman numeral).
'coming in' is an insertion indicator.
'shabby' indicates anagramming the letters.
'chalet' with letters rearranged gives 'ethcal'.
'i' placed inside 'ethcal' is 'ETHICAL'.
(Other definitions for ethical that I've seen before include "Abiding by moral principles" , "not advertised to the general public" , "Principled (behaviour)" , "lt's available on prescription only" , "In accordance with approved moral standards" .)