Select 100 stockings with hole in (6)
I believe the answer is:
choose
'select' is the definition.
(I know that select can be written as choose)
'100 stockings with hole in' is the wordplay.
'100' becomes 'C' (Roman numeral).
'stockings' becomes 'hose' (hose refers to stockings, tights etc).
'with' says to put letters next to each other.
'hole' becomes 'O'.
'in' is an insertion indicator.
'c'+'hose'='chose'
'chose' placed around 'o' is 'CHOOSE'.
(Other definitions for choose that I've seen before include "Pick, select." , "Make a selection" , "So echo (anag) - wish" , "Vote" , "Select, opt for" .)