First appearance as a featured East-Ender (5)
I believe the answer is:
start
'first' is the definition.
('start' can be a synonym of 'first')
'featured east-ender' is the wordplay.
'featured' becomes 'star' (I can't explain this - if you can you should give a lot more credence to this answer).
'ender' says to take the final letters (I've seen 'end' mean this).
The final letter of 'east' is 't'.
'star'+'t'='START'
'appearance as a' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for start that I've seen before include "Jerk" , "Begin - jump" , "Begin to recoil?" , "open" , "Begin - opening move" .)