Arms oddly go up nose (4)
I believe the answer is:
guns
'arms' is the definition.
(gun is a kind of arm)
'oddly go up nose' is the wordplay.
'oddly' indicates alternate letters.
'go'+'up'+'nose'='goupnose'
The alternating letters of 'goupnose' are 'GUNS'.
(Other definitions for guns that I've seen before include "Snug weapons?" , "Transportable armaments" , "Firearms" , "Bangers" .)