Upset, start to reside in temporary building (4)
I believe the answer is:
hurt
'upset' is the definition.
(I know that hurt is a type of upset)
'start to reside in temporary building' is the wordplay.
'start to' suggests taking the first letters.
'in' means one lot of letters goes inside another.
'temporary building' becomes 'hut' (hut can mean a temporary or basic building).
The initial letter of 'reside' is 'r'.
'r' going into 'hut' is 'HURT'.
(Other definitions for hurt that I've seen before include "Ache" , "Injured" , "Injure, pain" , "Injure - injury" , "Injure, harm" .)