Inspirational opening (7)
I believe the answer is:
nostril
'opening' is the definition.
(I know that nostril is a type of nostril)
I cannot understand how the rest of the clue works.
(Other definitions for nostril that I've seen before include "Breathing aperture" , "Nasal passage" , "Nasal opening" , "One of two holes in the head!" , "Nose hole" .)