Devil shown minus tail in March? (4)
I believe the answer is:
demo
'march?' is the definition.
(as in a demonstration)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for demo that I've seen before include "Protest (abbr)" , "Tape sent to recording studio" , "In brief, a public event as of protest under dome" , "Protest march (sl.)" , "Show" .)