Mopes about at racecourse (5)
I believe the answer is:
epsom
'racecourse' is the definition.
(I've seen this before)
'mopes about' is the wordplay.
'about' is an anagram indicator.
'mopes' with letters rearranged gives 'EPSOM'.
'at' acts as a link.
(Other definitions for epsom that I've seen before include "English racecourse" , "Town with racecourse" , "Derby town" , "Mopes around in English horse-racing venue" , "Derby area" .)