Yes, Brandt could be a spectator (9)
I believe the answer is:
bystander
'a spectator' is the definition.
(bystander is a kind of spectator)
'yes brandt could be' is the wordplay.
'could be' indicates an anagram.
'yes'+'brandt'='yesbrandt'
'yesbrandt' anagrammed gives 'BYSTANDER'.
(Other definitions for bystander that I've seen before include "Bad sentry may be an onlooker" , "Watcher of occurrence" , "Non-partcipating spectator" , "Non-participant spectator" , "Onlooker (often innocent)" .)