Course of a good person holding firm (5)
I believe the answer is:
ascot
'course' is the definition.
(I've seen this before)
'a good person holding firm' is the wordplay.
'good person' becomes 'st' (saint).
'holding' means one lot of letters goes inside another.
'firm' becomes 'co' (a firm is a company).
'st' enclosing 'co' is 'scot'.
'a'+'scot'='ASCOT'
'of' acts as a link.
(Other definitions for ascot that I've seen before include "Where ladies wear new hats" , "Racecourse, home to the Gold Cup since 1807" , "Racecourse near Windsor" , "Tosca (anag) - racecourse" , "Royal Berkshire race-meeting (and fashion show!)" .)