Descend by rope (6)
I believe the answer is:
abseil
'descend by rope' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for abseil that I've seen before include "Is able (anag.)" , "Come down a rock face using ropes" , "come down quickly" , "Descend vertically by rope" , "Use ropes to climb down a cliff face" .)