Tosca played in racecourse? (5)
I believe the answer is:
ascot
'racecourse?' is the definition.
(British racecourse)
'tosca played' is the wordplay.
'played' indicates an anagram.
'tosca' with letters rearranged gives 'ASCOT'.
'in' is the link.
(Other definitions for ascot that I've seen before include "Royal race course" , "English racecourse in Berkshire" , "Racecourse, home to the Gold Cup since 1807" , "Coats (anag) - racecourse" , "track" .)