Upper edge (4)
I believe the answer is:
brim
'upper edge' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for brim that I've seen before include "Lip; part of 6 Down" , "Lip of bowl, cup etc" , "The edge of a cup or glass" , "Top edge of a container" , "Topmost edge" .)