"River plaice" battered -- must be fake (7)
I believe the answer is:
replica
'fake' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'river plaice battered' is the wordplay.
'river' becomes 'r' (abbreviation).
'battered' indicates an anagram.
'plaice' anagrammed gives 'eplica'.
'r'+'eplica'='REPLICA'
'must be' acts as a link.
Can you help me to learn more?
(Other definitions for replica that I've seen before include "I parcel (anag) - reproduction" , "Reproduction, fascsimile" , "Copy original" , "Exact copy or model" , "Parcel I used to contain exact copy" .)