My lie is found out by an Englishman abroad (5)
I believe the answer is:
limey
'an englishman abroad' is the definition.
'my lie is found out' is the wordplay.
'is found out' indicates anagramming the letters (discovered out of the normal letter order).
'my'+'lie'='mylie'
'mylie' with letters rearranged gives 'LIMEY'.
'by' acts as a link.
(Other definitions for limey that I've seen before include "Briton" , "One of us in US" , "British person (in Australia)" , "British sailor" , "American and Australian term for British person" .)