Ignored at intervals, Doug's really revolutionary musical piece (5)
I believe the answer is:
largo
'musical piece' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for largo that I've seen before include "Slow passage" , "Slow and dignified tempo in music" , "Handel's piece?" , "major key" , "Deliberately" .)