Make sour beer after middle of November (8)
I believe the answer is:
embitter
'make sour' is the definition.
'beer after middle of november' is the wordplay.
'beer' becomes 'bitter' (I've seen this before).
'after' says to put letters next to each other.
'middle of' indicates the central letters.
The middle letters of 'november' are 'em'.
'bitter' put after 'em' is 'EMBITTER'.
(Other definitions for embitter that I've seen before include "Render hostile" , "Infect with ill-feeling or resentment" , "Make resentful and hostile" , "Alienate" , "Met tribe (anag) - make resentful" .)