Presumably, they get their marching orders in July from old crazy green man! (9)
I believe the answer is:
orangemen
'presumably they get their marching orders in july' is the definition.
The definition suggests an adverb but the answer is not.
'old crazy green man' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'crazy' is an anagram indicator.
'green'+'man'='greenman'
'greenman' anagrammed gives 'rangemen'.
'o'+'rangemen'='ORANGEMEN'
'from' is the link.
Can you help me to learn more?
(Other definitions for orangemen that I've seen before include "They wear sashes and march on July 12th" , "Loyalists" , "Colourful supporters of Protestantism in N Ireland" .)