A flier in black? (3)
I believe the answer is:
jet
'black?' is the definition.
('jet' can be similar in meaning to 'black')
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for jet that I've seen before include "Type of plane" , "Raven" , "Black gemstone" , "Black; spurt" , "Black variety of lignite, used for ornaments" .)