Old coastal area is excellent, best seen from the east (5)
I believe the answer is:
ionia
'old coastal area' is the definition.
'Ionia' can be an answer for 'area' (Ionia is an example). I am not sure about the 'old coastal' bit.
'excellent best seen from the east' is the wordplay.
'excellent' becomes 'ai' (resembles 'An', old-fashioned term for excellent).
'best seen' becomes 'noi' (I can't justify this - if you can you should believe this answer much more).
'from the east' is a reversal indicator (on a map from right to left).
'ai'+'noi'='ainoi'
'ainoi' backwards is 'IONIA'.
'is' is the link.
Can you help me to learn more?
(Other definitions for ionia that I've seen before include "Ancient region of Asia Minor" , "East coast of the Aegean in Classical times" , "Ancient area" , "ancient region of Eastern Mediterranean" , "Classical Aegean region" .)