Revisit UN building uninvited? (9)
I believe the answer is:
intrusive
'uninvited?' is the definition.
('intrusive' can be similar in meaning to 'uninvited')
'revisit un building' is the wordplay.
'building' indicates an anagram.
'revisit'+'un'='revisitun'
'revisitun' anagrammed gives 'INTRUSIVE'.
(Other definitions for intrusive that I've seen before include "Coming in uninvited" , "Unwelcome, being alien" , "Meddlesome" , "Being present uninvited" , "Presumptuous" .)