Explosion of air from the nose (6)
I believe the answer is:
sneeze
'explosion of air from the nose' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for sneeze that I've seen before include "Sudden, involuntary and noisy spasm" , "sign of cold > work by 3 [FRAYN]" , "Inadvertent explosion of air" , "Explosive nasal action" , "Sudden involuntary expulsion of air" .)