Laces on running shoes (6)
I believe the answer is:
spikes
I believe this is a double definition.
'laces' is the first definition.
(I know this)
'running shoes' is the second definition.
(I've seen this before)
'on' acts as a link.
(Other definitions for spikes that I've seen before include "Makes (a gun) useless" , "Running shoes" , "Prongs" , "Sharp points on athletes' shoes" .)