Genius running oxygen tunnel into nose (7)
I believe the answer is:
prodigy
'genius' is the definition.
(I know that prodigy is a type of genius)
'oxygen tunnel into nose' is the wordplay.
'oxygen' becomes 'O' (atomic symbol for oxygen).
'tunnel' becomes 'dig' (I can't justify this - if you can you should believe this answer much more).
'into' is an insertion indicator.
'nose' becomes 'pry' (to nose around is to pry).
'o'+'dig'='odig'
'odig' inserted into 'pry' is 'PRODIGY'.
'running' is the link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for prodigy that I've seen before include "Amazing thing" , "Youngster of exceptional abilities" , "Amazingly talented child" , "Child genius" .)