Smithy; counterfeit (5)
I believe the answer is:
forge
This clue is a double definition.
'smithy' is the first definition.
(synonyms)
'counterfeit' is the second definition.
(I know that counterfeit can be written as forge)
(Other definitions for forge that I've seen before include "Counterfeit - smithy" , "Create; counterfeit" , "Ironworks" , "Blacksmith's premises" , "Smith's workshop" .)