Alan's wrong to be nosy (5)
I believe the answer is:
nasal
'be nosy' is the definition.
(relating to the nose)
'alan's wrong' is the wordplay.
'wrong' is an anagram indicator.
'alans' anagrammed gives 'NASAL'.
'to' acts as a link.
(Other definitions for nasal that I've seen before include "Relating to the nose" , "Rhinal" , "Of sound, as if it came through the nose" , "Describing some hooter" , "nozzle" .)