Characters in winter value break in activity (8)
I believe the answer is:
interval
'break in activity' is the definition.
(I've seen this before)
'characters in winter value' is the wordplay.
'characters in' indicates the answer is hidden within the clue.
'INTERVAL' can be found hidden inside 'winter value'.
(Other definitions for interval that I've seen before include "Gap during performance" , "Time to read programme notes, perhaps" , "Short break" , "A break as in travel" , "Space of time" .)