One has to go and look inside so cold a house (5)
I believe the answer is:
igloo
'house' is the definition.
(I've seen this before)
'one has to go and look inside so' is the wordplay.
'one has to go' becomes 'ig' (I am not sure about this - if you are sure you should believe this answer much more).
'and' says to put letters next to each other.
'look' becomes 'lo' (archaic exclamation meaning 'look!').
'inside' indicates the central letters.
'so' becomes 'too' (synonyms).
The middle letter of 'too' is 'o'.
'ig'+'lo'+'o'='IGLOO'
'cold a' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for igloo that I've seen before include "Traditional Inuit house" , "series of chilly blocks" , "An eskimo's ice-house" , "Eskimo's home" , "Snow dwelling" .)