Spike attached to stone overhangs (5)
I believe the answer is:
piton
'spike' is the definition.
(I know that piton is a type of spike)
'attached to stone overhangs' is the wordplay.
I cannot really see how this works, but
'attached' could be 'on' (I've seen this in other clues) and 'on' is found within the answer.
'stone' could be 'pit' (synonyms) and 'pit' is found in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for piton that I've seen before include "Metal peg used in rock climbing" , "In top (anag.)" , "Peg driven into rock as climbing support" , "Climber's iron peg" , "Mountaineering tool" .)