Run left before snake (6)
I believe the answer is:
ladder
'run' is the definition.
(both can mean a rip in tights)
'left before snake' is the wordplay.
'left' becomes 'l' (common abbreviation).
'before' is a charade indicator (letters next to each other).
'snake' becomes 'adder' (type of snake).
'l'+'adder'='LADDER'
(Other definitions for ladder that I've seen before include "Vertical run in tights" , "something that can send you in the opposite direction?" , "Steps consisting of rungs" , "sort of tournament" , "Opposite of snake?" .)