Gathers hard work is in store for pupils (4,4)
I believe the answer is:
tuck shop
'store for pupils' is the definition.
The definition suggests a singular noun which matches the answer.
'gathers hard work' is the wordplay.
'gathers' becomes 'tucks' ('tuck' can be a synonym of 'gather').
'hard' becomes 'h' (abbreviation used in pencil classifications).
'work' becomes 'op' (abbreviation for opus).
'tucks'+'h'+'op'='TUCK-SHOP'
'is in' is the link.
Can you help me to learn more?
(Other definitions for tuck shop that I've seen before include "Place to get food and drink" , "Candy store for students" , "Schoolboys' source of sweets etc" , "(School) snacks seller" , "Charterhouse store" .)