It helps to climb, walk and run (10)
I believe the answer is:
stepladder
'it helps to climb' is the definition.
(a stepladder can be used to climb to a height)
'walk and run' is the wordplay.
'walk' becomes 'step' (I've seen this before).
'and' means one lot of letters go next to another.
'run' becomes 'ladder' (both can mean a rip in tights).
'step'+'ladder'='STEPLADDER'
(Other definitions for stepladder that I've seen before include "Portable climbing aid" , "Domestic climbing aid" , "Decorator's platform" , "Short folding climbing frame" , "piece of equipment" .)