Prevents the opening of a shop for toys (5)
I believe the answer is:
stops
'prevents' is the definition.
(stopping is a kind of preventing)
'opening of a shop for toys' is the wordplay.
'opening of' indicates taking the first letters.
'for' means one lot of letters go next to another.
'toys' becomes 'tops' (top is a kind of toy).
The initial letter of 'shop' is 's'.
's'+'tops'='STOPS'
'the' is the link.
(Other definitions for stops that I've seen before include "Checks" , "Halts" , "Discontinues" , "Ceases" , "Prevents" .)