Escape heading away from dreary season (7)
I believe the answer is:
leakage
'escape' is the definition.
('leakage' can be a synonym of 'escape')
'heading away from dreary season' is the wordplay.
'heading away from' means to remove the first letter.
'dreary' becomes 'bleak'.
'season' becomes 'age'.
'bleak' with its initial letter taken off is 'leak'.
'leak'+'age'='LEAKAGE'
(Other definitions for leakage that I've seen before include "Accidental loss of fluid" , "Escaping liquid or gas" , "Escape of liquid or gas - or confidential information" , "Lake age (anag.)" , "Accidental escape (of a liquid or gas)" .)