Battle spirit adopted by a tribunal (9)
I believe the answer is:
agincourt
'battle' is the definition.
(Agincourt is an example)
'spirit adopted by a tribunal' is the wordplay.
'spirit' becomes 'gin' (alcoholic spirit).
'adopted by' means one lot of letters goes inside another (I've seen this in other clues).
'tribunal' becomes 'court' (synonyms).
'a'+'court'='acourt'
'gin' inserted into 'acourt' is 'AGINCOURT'.
(Other definitions for agincourt that I've seen before include "battle site" , "Battleground" , "Henry V's battle" , "English-French battle" , "where Henry met Constable" .)