Joint protection from men on board, with movement for peace (7)
I believe the answer is:
kneecap
'joint protection' is the definition.
(knee joint)
'men on board with movement for peace' is the wordplay.
I cannot really see how this works, but
an anagram of 'peace' is 'eecap' which is present in the answer.
This explanation may well be incorrect...
'from' acts as a link.
(Other definitions for kneecap that I've seen before include "Bone" , "part of joint" , "one going on bender?" , "Horribly punish" , "The informal patella (7)" .)