Sit in a loo, uneasily, in solitude (9)
I believe the answer is:
isolation
'solitude' is the definition.
(thesaurus)
'sit in a loo uneasily' is the wordplay.
'uneasily' indicates an anagram.
'sit'+'in'+'a'+'loo'='sitinaloo'
'sitinaloo' with letters rearranged gives 'ISOLATION'.
'in' is the link.
(Other definitions for isolation that I've seen before include "Staff in such a hospital working with" , "Detachment" , "Cutting off" , "State of being alone" , "State of separation, closing off" .)