One judge may be very cross (5)
I believe the answer is:
irate
'be very cross' is the definition.
(I've seen this before)
'one judge' is the wordplay.
'one' becomes 'i' (Roman numeral).
'judge' becomes 'rate' (rating is a kind of judging).
'i'+'rate'='IRATE'
'may' acts as a link.
(Other definitions for irate that I've seen before include "Not happy" , "Angry and incensed" , "Full of 22" , "having got in wax" , "become irritated" .)