Descend on ropes (6)
I believe the answer is:
abseil
'descend on ropes' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for abseil that I've seen before include "Descend rock face on rope" , "Climb down using a double rope" , "Descend using running rope" , "Slide down on rope" , "Isabel (anag) - descend a cliff by rope" .)