In verdict, umpire's given authoritative statement (6)
I believe the answer is:
dictum
'authoritative statement' is the definition.
(I've seen this before)
'in verdict umpire's given' is the wordplay.
'in' indicates a hidden word.
'DICTUM' is hidden within 'verdict umpires given'.
(Other definitions for dictum that I've seen before include "Decree; maxim" , "Authoritative declaration" , "Formal pronouncement" , "Authoritative pronouncement" , "Fiat" .)