Nosy, first to look a veteran nursing home over (5)
I believe the answer is:
nasal
'nosy' is the definition.
(relating to the nose)
'first to look a veteran nursing home over' is the wordplay.
'first to' indicates taking the first letters.
'a veteran nursing home' becomes 'nasa' (I can't justify this - if you can you should believe this answer much more).
'over' means one lot of letters go next to another (in a down clue, some letters go over others).
The first letter of 'look' is 'l'.
'l' after 'nasa' is 'NASAL'.
Can you help me to learn more?
(Other definitions for nasal that I've seen before include "Part of helmet" , "Sniffer's" , "front piece of helmet" , "description of Alain's vowels" , "regarding the nose" .)