Short section within winter session (5)
I believe the answer is:
terse
'short' is the definition.
('terse' can be a synonym of 'short')
'section within winter session' is the wordplay.
'section' indicates the answer is hidden within the clue.
'TERSE' is hidden in the letters of 'within winter session'.
(Other definitions for terse that I've seen before include "Curtly brief" , "Curt, laconic of speech" , "Short and to the point" , "Brusque among trees" , "Brusque and curt" .)