Greeting Scottish banker and a rising religious leader (9)
I believe the answer is:
ayatollah
'religious leader' is the definition.
(type of religious leader in Islam)
'greeting scottish banker and a rising' is the wordplay.
'greeting' becomes 'hallo' (alternative to hello).
'scottish banker' becomes 'Tay' (Tay is a Scottish river - something with banks).
'and' says to put letters next to each other.
'rising' shows that the letters should be reversed in order (going up in a down clue).
'hallo'+'tay'+'a'='hallotaya'
'hallotaya' written backwards gives 'AYATOLLAH'.
(Other definitions for ayatollah that I've seen before include "Senior Iranian cleric" , "High-ranking Shiite religious leader" , "Shiite leader, possibly in 10 across" , "Muslim leader" , "Iranian leader" .)