First-class society to delight in (4-2)
I believe the answer is:
slap-up
'first-class' is the definition.
(eg a slap-up meal, an excellent meal)
'society to delight in' is the wordplay.
'society' becomes 's' (common abbreviation in names of organisations).
'to delight in' becomes 'lapup' (to lap something up is to delight in it).
's'+'lapup'='SLAP-UP'
(Other definitions for slap-up that I've seen before include "Lavish, meal say" , "This meal is first-class" , "With no expense spared" , "Of meal, rich and plentiful" , "Very good, meal say" .)