Difficult to hide ring in secret store (5)
I believe the answer is:
hoard
'secret store' is the definition.
(I've seen this before)
'difficult to hide ring' is the wordplay.
'difficult' becomes 'hard' ('hard' can be a synonym of 'difficult').
'to hide' indicates putting letters inside.
'ring' becomes 'o'.
'hard' placed around 'o' is 'HOARD'.
'in' is the link.
(Other definitions for hoard that I've seen before include "Accumulated store" , "Amass secretly" , "Amass and store privately" , "A lot of people" , "Squirrel away" .)