Mission leading to manoeuvres round end of battle (10)
I believe the answer is:
delegation
'mission' is the definition.
('delegation' can be a synonym of 'mission')
'leading to manoeuvres round end of battle' is the wordplay.
'manoeuvres' is an anagram indicator.
'round' indicates putting letters inside.
'end of' indicates one should take the final letters.
The last letter of 'battle' is 'e'.
'leading'+'to'='leadingto'
'leadingto' with letters rearranged gives 'delgation'.
'delgation' placed around 'e' is 'DELEGATION'.
(Other definitions for delegation that I've seen before include "representative group" , "Passing over" .)