Remarkable Belgians performing, not live (6)
I believe the answer is:
signal
'remarkable' is the definition.
(signal can mean striking or noteworthy)
I cannot understand how the rest of the clue works.
(Other definitions for signal that I've seen before include "Communication with encoded message" , "Communication by sign" , "Remarkable; gesture" , "Gesture to convey information" , "Gesture with meaning" .)