Racecourse record thus misrepresented at first (5)
I believe the answer is:
epsom
'racecourse' is the definition.
(Epsom is an English racecourse)
'record thus misrepresented at first' is the wordplay.
'record' becomes 'EP' (abbreviation for extended play record).
'thus' becomes 'so' (synonyms).
'at first' suggests taking the first letters.
The initial letter of 'misrepresented' is 'm'.
'ep'+'so'+'m'='EPSOM'
(Other definitions for epsom that I've seen before include "Derby and Oaks racecourse" , "Mopes around in English horse-racing venue" , "Poems about the race-course" , "Surrey race course" , "- Salts are a purgative" .)