Middle of trial: judge becomes furious (5)
I believe the answer is:
irate
'furious' is the definition.
(I've seen this before)
'middle of trial judge' is the wordplay.
'middle of' indicates the central letters.
'judge' becomes 'rate' (rating is a kind of judging).
The central letter of 'trial' is 'i'.
'i'+'rate'='IRATE'
'becomes' acts as a link.
(Other definitions for irate that I've seen before include "Full of 22" , "Spitting feathers" , "Not happy" , "Hacked off" , "Annoyed, nettled" .)