Step of ladder, right in the centre (4)
I believe the answer is:
rung
'step' is the definition.
(I've seen this before)
'ladder right in the centre' is the wordplay.
'ladder' becomes 'run' (both can mean a tear in tights).
'in the centre' means to look at the middle letters.
The central letter of 'right' is 'g'.
'run'+'g'='RUNG'
'of' is the link.
(Other definitions for rung that I've seen before include "Horizontal bar in ladder" , "Ladder's step" , "Part of a ladder" , "Level in a hierarchy" , "Phoned" .)