Criticise a Society in decline (5)
I believe the answer is:
roast
'criticise' is the definition.
(thesaurus)
'a society in decline' is the wordplay.
'society' becomes 's' (common abbreviation in names of organisations).
'in' means one lot of letters goes inside another.
'decline' becomes 'rot' (I've seen this before).
'a'+'s'='as'
'as' placed inside 'rot' is 'ROAST'.
(Other definitions for roast that I've seen before include "One way to cook meat" , "Traditional Sunday lunch" , "Honey-based drink" , "Cooked like chestnuts tonight" , "Cook in oven or by exposure to heat" .)