Uniform for Trim meeting (4)
I believe the answer is:
even
'uniform' is the definition.
(thesaurus)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for even that I've seen before include "Flat, regular" , "Not easily annoyed" , "Flat, level" , "Flat - yet" , "without a rise?" .)