Brief encountered in quarter sessions (5)
I believe the answer is:
terse
'brief' is the definition.
(synonyms)
'encountered in quarter sessions' is the wordplay.
'encountered in' indicates a hidden word.
'TERSE' can be found hidden inside 'quarter sessions'.
(Other definitions for terse that I've seen before include "Short and sharp" , "Pithy and concise" , "Curt, laconic of speech" , "Curtly brief" , "Short and to the point" .)