Season's yield -- unusual haste to gather in right volume (7)
I believe the answer is:
harvest
'season's' is the definition.
(harvest is a kind of season)
'unusual haste to gather in right volume' is the wordplay.
'unusual' is an anagram indicator.
'to gather' indicates putting letters inside.
'in right' becomes 'r' (common abbreviation. I am not sure about the 'in' bit.).
'volume' becomes 'v' (abbreviation for volume in book titles).
'haste' is an anagram of 'haest'.
'r'+'v'='rv'
'haest' going around 'rv' is 'HARVEST'.
'yield' acts as a link.
Can you help me to learn more?
(Other definitions for harvest that I've seen before include "seasonal collection" , "Crops gathered in" , "Seasonal yield" , "reap rewards" , "Bring in the corn etc" .)