Good record for the upper classes (6)
I believe the answer is:
gentry
'upper classes' is the definition.
(I've seen this before)
'good record' is the wordplay.
'good' becomes 'g' (abbreviation).
'record' becomes 'entry' (eg entry in a list).
'g'+'entry'='GENTRY'
'for the' acts as a link.
(Other definitions for gentry that I've seen before include "who are noble" , "Class of society" , "Nobs" , "People of a social position just below the nobility" , "People of social rank just below nobility" .)