Step ladder good (4)
I believe the answer is:
rung
'step' is the definition.
(I've seen this in another clue)
'ladder good' is the wordplay.
'ladder' becomes 'run' (both can mean a tear in tights).
'good' becomes 'g' (abbreviation).
'run'+'g'='RUNG'
(Other definitions for rung that I've seen before include "Ladder's step" , "Level in a hierarchy" , "Crosspiece of a ladder" , "support for foot" , "spoke" .)