Pointless climbing - without this? (5)
I believe the answer is:
piton
'pointless climbing without this?' is the definition.
The definition suggests a singular noun which matches the answer.
'climbing without this?' is the wordplay.
'climbing' says the letters should be written backwards (in a down clue, letters climb up).
'without' becomes 'not'.
'this?' becomes 'ip' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'not'+'ip'='notip'
'notip' written backwards gives 'PITON'.
Can you help me to learn more?
(Other definitions for piton that I've seen before include "Kind of rope-supporting peg used in rock-climbing" , "In top (anag.)" , "Mountaineering tool" , "Spike to support a climber" , "Mountaineer's metal spike" .)