I had a little house in US region (5)
I believe the answer is:
idaho
'us region' is the definition.
'Idaho' can be an answer for 'region' (Idaho is an example). I'm not certain of the 'us' bit.
'i had a little house' is the wordplay.
'i had' becomes 'I'd' (common contraction).
'a' becomes 'an'.
'little' means to remove the last letter (the word is not quite complete).
'house' becomes 'ho' (abbreviation for house).
'id'+'an'='idan'
'idan' with its last letter removed is 'ida'.
'ida'+'ho'='IDAHO'
'in' is the link.
Can you help me to learn more?
(Other definitions for idaho that I've seen before include "somewhere in the US" , "part of US near Washington" , "US state, capital Boise" , "found in America" , "O, I had a change in this state" .)