Even out till the early hours, apostle briefly pops round (7)
I believe the answer is:
plateau
'even out' is the definition.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for plateau that I've seen before include "High tableland" , "High plain" , "plane" , "Area of livel high ground" , "Tract of tableland" .)