Number Ten has ruined European continent's housing (11)
I believe the answer is:
anaesthesia
'number' is the definition.
(something which numbs)
'ten has ruined european continent's housing' is the wordplay.
'ruined' indicates an anagram.
'european' becomes 'e' (abbreviation e.g. EU).
'continent' becomes 'asia' (Asia is an example).
'housing' indicates putting letters inside.
'ten'+'has'='tenhas'
'tenhas' is an anagram of 'naesth'.
'naesth'+'e'='naesthe'
'naesthe' inserted within 'asia' is 'ANAESTHESIA'.
(Other definitions for anaesthesia that I've seen before include "Drug-induced insensitivity to pain" , "Loss of feeling through administered drugs" , "Insensitivity to pain induced by drugs" .)