Every year abolish almost everything by end of January (8)
I believe the answer is:
annually
'every year' is the definition.
('annually' can be a synonym of 'every year')
'abolish almost everything by end of january' is the wordplay.
'abolish' becomes 'annul' (I've seen this before).
'almost' means to remove the last letter (most of the word but not all of it).
'everything' becomes 'all' (I've seen this before).
'by' says to put letters next to each other.
'end of' says to take the final letters.
The last letter of 'january' is 'y'.
'annul' with its final letter removed is 'annu'.
'annu'+'all'+'y'='ANNUALLY'
(Other definitions for annually that I've seen before include "Every year" , "at regular intervals" , "As Christmas is coming" , "as MOTs must be renewed" .)