A wave involving people for the accord (9)
I believe the answer is:
agreement
'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'.
'a'+'greement'='AGREEMENT'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for agreement that I've seen before include "Compact, accord" , "Harmony or treaty" , "deal" , "legal contract maybe" , "Contract or promise" .)