Pretentious, admitting one’s turning up with affected voice (9)
I believe the answer is:
adenoidal
'affected voice' is the definition.
(I've seen this before)
'pretentious admitting one's turning up' is the wordplay.
'pretentious' becomes 'la-di-da' (la-di-da means pretentious or fancy).
'admitting' indicates putting letters inside (admit can mean to welcome in or accept).
'turning up' says the letters should be written backwards.
'ladida' enclosing 'one' is 'ladioneda'.
'ladioneda' backwards is 'ADENOIDAL'.
'with' is the link.
(Other definitions for adenoidal that I've seen before include "Having nasal tones" , "affected voice" , "Like glandular tissue at back of nose" , "concerning pharyngeal tonsil" , "with a nasal voice?" .)