Top messenger sees a variation between right and left (9)
I believe the answer is:
archangel
'top messenger' is the definition.
'archangel' can be an answer for 'messenger' (I have seen 'Senior messenger' mean 'archangel' so perhaps 'messenger' could also mean 'archangel'). I am unsure of the 'top' bit.
'a variation between right and left' is the wordplay.
'variation' becomes 'change' (I can't justify this - if you can you should give a lot more credence to this answer).
'between' is an insertion indicator.
'right' becomes 'r' (common abbreviation).
'and' is a charade indicator (letters next to each other).
'left' becomes 'l' (common abbreviation).
'r'+'l'='rl'
'change' going within 'rl' is 'rchangel'.
'a'+'rchangel'='ARCHANGEL'
'sees' acts as a link.
Can you help me to learn more?
(Other definitions for archangel that I've seen before include "Pigeon" , "Port in northern Russia, or senior heavenly messenger" , "Divine messenger - Russian port" , "What we call a port" , "Russian city" .)