Small crudely built house is closed (4)
I believe the answer is:
shut
'is closed' is the definition.
(synonyms)
'small crudely built house' is the wordplay.
I cannot really see how this works, but
'small' could be 's' (abbreviation - e.g. clothes size) and 's' is found in the answer.
'house' could be 'hut' (I have seen 'Small house ' mean 'hut' so perhaps 'house' could also mean 'hut') and 'hut' is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for shut that I've seen before include "Draw to" , "See 19" , "Out of business" , "Close" , "Closed" .)