"Fake!!, Peatfield states (5)
I believe the answer is:
bogus
'fake' is the definition.
(synonyms)
'peatfield states' is the wordplay.
'peatfield' becomes 'bog' (I am not sure about this - if you are sure you should believe this answer much more).
'states' becomes 'US' (abbreviation for the United States).
'bog'+'us'='BOGUS'
Can you help me to learn more?
(Other definitions for bogus that I've seen before include "Fake, phoney" , "false impression" , "Dummy" , "Sham, counterfeit" , "Not genuine, sham" .)