On Sunday cabin is closed (4)
I believe the answer is:
shut
'is closed' is the definition.
(synonyms)
'on sunday cabin' is the wordplay.
'on' is a charade indicator (letters next to each other).
'sunday' becomes 's'.
'cabin' becomes 'hut' (both can mean a small building).
's' put next to 'hut' is 'SHUT'.
(Other definitions for shut that I've seen before include "not accepting visitors" , "Push to" , "Out of business" , "See 19" , "Draw to" .)