Butcher regularly flipped old coin (3)
I believe the answer is:
ecu
'old coin' is the definition.
(I've seen this in other clues)
'butcher regularly flipped' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'flipped' shows that the letters should be reversed in order.
The alternating letters of 'butcher' are 'uce'.
'uce' back-to-front is 'ECU'.
(Other definitions for ecu that I've seen before include "Former term for Euro" , "coin once minted in France" , "Old European currency unit" , "Original name of euro" , "European money unit; old French coin" .)