A step up the ladder (4)
I believe the answer is:
rung
'a step up the ladder' is the definition.
(I've seen this before)
'ladder' is the wordplay.
I cannot really understand how this works, but
'ladder' could be 'run' (both can mean a tear in tights) and 'run' is present in the answer.
A single letter 'g' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for rung that I've seen before include "Part of a ladder" , "spoke" , "Telephoned" , "Crosspiece of a ladder" , "Ladder's step" .)