The head celestial messenger (9)
I believe the answer is:
archangel
'the head celestial messenger' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for archangel that I've seen before include "Among others, Michael" , "celestial flier" , "foreign port" , "Senior heavenly messenger or Russian port" , "Senior spirit; Russian port" .)