A wave involving people for the accord (9)
I believe the answer is:
Here is my best explanation:
'the accord' is the definition.
('agreement' can be a synonym of 'accord')
'a wave involving people' is the wordplay.
'wave' becomes 'greet' (I can't justify this - if you can you should believe this answer much more).
'involving' is an insertion indicator.
'people' becomes 'men' (men can refer to humanity as a whole).
'greet' placed around 'men' is 'greement'.
'for' acts as a link.