Prevent plot being designed to wound (6)
I believe the answer is:
barbed
'designed to wound' is the definition.
(as in a barbed comment)
'prevent plot' is the wordplay.
'prevent' becomes 'bar' (both can mean to ban or disallow).
'plot' becomes 'bed' (a plot of land).
'bar'+'bed'='BARBED'
'being' is the link.
(Other definitions for barbed that I've seen before include "Wounding, spiteful" , "Pointed or wounding, words or wire" , "Wire and remarks may be" , "Mordant, scathing" , "Having sharp spikes, wire or comment" .)