Item of hosiery (4)
(Other definitions for sock that I've seen before include "Hit hard - footwear" , "Hit; garment" , "bash" , "One worn" , "component of Christmas present" .)
'item of hosiery' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for tights that I've seen before include "Hose coverings from waist to feet" , "Item of hosiery" , "Close fitting garment" , "Women's garment worn in place of stockings" , "Woman's garment" .)