It's good in one privy in packed house (5)
I believe the answer is:
igloo
'packed house' is the definition.
(I've seen this before)
'it's good in one privy' is the wordplay.
'it's good' becomes 'g' (abbreviation).
'in' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'privy' becomes 'loo' (loo is a kind of privy).
'i'+'loo'='iloo'
'g' inserted inside 'iloo' is 'IGLOO'.
'in' is the link.
(Other definitions for igloo that I've seen before include "packed house" , "cold accommodation" , "home in the cold" , "basic dwelling" , "Ice-block construction" .)