Retailer will have miniature replicas by spring (7)
I believe the answer is:
toyshop
'retailer will' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'miniature replicas by spring' is the wordplay.
'miniature' becomes 'toy' (synonyms).
'replicas by' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'spring' becomes 'hop' (hopping is a kind of springing).
'toy'+'s'+'hop'='TOYSHOP'
'have' is the link.
Can you help me to learn more?
(Other definitions for toyshop that I've seen before include "Emporium favoured by children" , "Source of amusements" , "Hamleys, say," , "Establishment selling playthings" , "Heavenly place for a child perhaps" .)