'Rotting food swindle' admits épicier, finally, in the middle of Paris (7)
I believe the answer is:
carrion
'rotting food' is the definition.
'swindle admits epicier finally in the middle of paris' is the wordplay.
'swindle' becomes 'con' (con is a kind of swindle).
'admits' means one lot of letters goes inside another.
'finally' suggests the final letters.
'in' is an insertion indicator.
'the middle of' indicates the central letters.
The centre of 'paris' is 'ari'.
The last letter of 'epicier' is 'r'.
'r' going inside 'ari' is 'arri'.
'con' going around 'arri' is 'CARRION'.
(Other definitions for carrion that I've seen before include "Decaying animal flesh" , "Food for crow" , "Dead meat as food" , "Cor! Rain! (anag.)" , "Rotting flesh of dead animals" .)