Poisoned quotes protecting power on the rise (6)
I believe the answer is:
septic
'poisoned' is the definition.
(I've seen this before)
'quotes protecting power on the rise' is the wordplay.
'quotes' becomes 'cites' ('cite' can be a synonym of 'quote').
'protecting' indicates putting letters inside (inserted letters are held or protected).
'power' becomes 'p'.
'on the rise' shows that the letters should be reversed in order.
'cites' enclosing 'p' is 'citpes'.
'citpes' reversed gives 'SEPTIC'.
(Other definitions for septic that I've seen before include "Of wound, forming pus" , "Relating to putrefaction" , "Of wound, filled with pus" , "Type of tank" , "Infected with bacteria" .)