Climbing aid's special point (5)
I believe the answer is:
piton
'climbing aid's' is the definition.
(spike used by a climber)
'special point' is the wordplay.
'special' indicates an anagram.
'point' is an anagram of 'PITON'.
(Other definitions for piton that I've seen before include "Peg driven into rock to aid climbing" , "Climber's tool" , "something used when climbing" , "In top (anag.)" , "Peg driven into rock as climbing support" .)