There's nothing in perplexing secret store (5)
I believe the answer is:
hoard
'secret store' is the definition.
(I've seen this in another clue)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for hoard that I've seen before include "A lot of people" , "Hard kick" , "Store of money or valuables" , "Hidden stock" , "Store, usually hidden" .)