Remarkable apparatus for conveying information (6)
I believe the answer is:
signal
'remarkable' is the definition.
(signal can mean striking or noteworthy)
'apparatus for conveying information' is the wordplay.
I cannot quite understand how this works, but
'information' could be 'sign' (sign is a kind of information) and 'sign' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for signal that I've seen before include "Notable; warning sign" , "Gesture with meaning" , "Important; gesture" , "intimation" , "beacon" .)