Ezra confused about uniform blue (5)
I believe the answer is:
azure
'blue' is the definition.
(azure is a kind of blue)
'ezra confused about uniform' is the wordplay.
'confused' indicates anagramming the letters.
'about' indicates putting letters inside.
'uniform' becomes 'u' (phonetic alphabet: alpha, bravo, charlie etc.).
'ezra' with letters rearranged gives 'azre'.
'azre' enclosing 'u' is 'AZURE'.
(Other definitions for azure that I've seen before include "Description of sky, perhaps" , "Heraldic blue" , "heraldic colour?" , "Blue like the sky" , "Bright blue" .)