Regular servings of chow mein arrive (4,2)
I believe the answer is:
come in
'arrive' is the definition.
(I know that come in is a kind of arrive)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for come in that I've seen before include "arrive" , "Enter, don't stay outside" , "Enter - from the cold?" , "Enter - you're invited" .)