To pin, perhaps, with a spike (5)
I believe the answer is:
piton
'a spike' is the definition.
(piton is a kind of spike)
'to pin perhaps' is the wordplay.
'perhaps' is an anagram indicator.
'to'+'pin'='topin'
'topin' is an anagram of 'PITON'.
'with' is the link.
(Other definitions for piton that I've seen before include "Spike to support a climber" , "climber needs this" , "something upwardly mobile type hammers home" , "Peg used in mountaineering" , "It helps the climber" .)