Fearful, Stefan regularly avoided Oriental waters (6,3)
I believe the answer is:
yellow sea
'oriental waters' is the definition.
'fearful stefan regularly avoided' is the wordplay.
'fearful' becomes 'yellow' ('yellow' can be similar in meaning to 'fearful').
'regularly avoided' indicates alternate letters.
The alternate letters of 'stefan' are 'sea'.
'yellow'+'sea'='YELLOW SEA'
(Other definitions for yellow sea that I've seen before include "Ocean to W of Korean peninsula" , "Waters around China" , "Eastern ocean" , "main area" , "water from the east" .)