Politician supporting closures from January to March (4)
I believe the answer is:
yomp
'to march' is the definition.
(I have seen 'Difficult March' mean 'yomp' so perhaps 'march' could also mean 'yomp')
'politician supporting closures from january' is the wordplay.
'politician' becomes 'MP' (Member of Parliament).
'supporting' means one lot of letters go next to another (in a down clue, some letters go below others).
'closures from january' becomes 'yo' (I can't justify this - if you can you should believe this answer much more).
'mp' put after 'yo' is 'YOMP'.
Can you help me to learn more?
(Other definitions for yomp that I've seen before include "Make difficult march" , "March carrying full kit" , "March laden" , "Determined trek" , "Walk carrying heavy equipment (military sl.)" .)