British directive for march (6)
I believe the answer is:
border
'march' is the definition.
(thesaurus)
'british directive' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'directive' becomes 'order' (I've seen this before).
'b'+'order'='BORDER'
'for' acts as a link.
(Other definitions for border that I've seen before include "Line that indicates a boundry" , "Rim" , "skirt" , "Edging" , "Frontier of a country" .)