Finally organising diverse people into rank and order (11)
I believe the answer is:
arrangement
'order' is the definition.
(I've seen this before)
'finally organising diverse people into rank' is the wordplay.
'finally' indicates one should take the final letters.
'people' becomes 'men' (men are people).
'into' is an insertion indicator.
'rank' becomes 'arrant' (synonyms).
The final letters of 'organising diverse' are 'ge'.
'ge'+'men'='gemen'
'gemen' inserted into 'arrant' is 'ARRANGEMENT'.
'and' is the link.
(Other definitions for arrangement that I've seen before include "configuration" , "Adaptation - understanding" , "Organisation, plan" , "terms" , "Plan; settlement" .)