Brass still coating rupees from the east (5)
I believe the answer is:
nerve
'brass' is the definition.
(I know that brass can be written as nerve)
'coating rupees from the east' is the wordplay.
'coating' is an insertion indicator.
'rupees' becomes 'r' (abbreviation for rupees).
'from' becomes 'nev' (I am not sure about this - if you are sure you should believe this answer much more).
'the east' becomes 'E' (abbreviation).
'r' put within 'nev' is 'nerv'.
'nerv'+'e'='NERVE'
'still' acts as a link.
I am not very happy about this link. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for nerve that I've seen before include "Brass neck" , "Strand of body tissue" , "Dangerous type of gas" , "Bundles of fibres in the body that transmit instructions" , "Bundle of fibres < in face" .)