"Bed-Ins for Peace” participant (3)
I believe the answer is:
ono
'bed-ins for peace participant' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ono that I've seen before include "Singer's wife" , "Or nearest offer (abbr.)" , "Yoko ..., wife of John Lennon" .)