A Glaswegian say in Berkshire town (5)
I believe the answer is:
ascot
'berkshire town' is the definition.
(town in Berkshire)
'a glaswegian say' is the wordplay.
'glaswegian say' becomes 'Scot' (glaswegian is a kind of Scot).
'a'+'scot'='ASCOT'
'in' acts as a link.
(Other definitions for ascot that I've seen before include "where some of our betters may be" , "Posh racecourse" , "Coats (anag) - racecourse" , "Tie round the neck" , "Type of necktie" .)