Festivity containing posh cooked meat in country (9)
I believe the answer is:
guatemala
'country' is the definition.
(Guatemala is an example)
'festivity containing posh cooked meat' is the wordplay.
'festivity' becomes 'gala' (gala is a kind of festivity**).
'containing' indicates putting letters inside.
'posh' becomes 'u' (abbreviation for upper-class - opposite to non-u).
'cooked' indicates an anagram.
'meat' with letters rearranged gives 'atem'.
'u'+'atem'='uatem'
'gala' placed around 'uatem' is 'GUATEMALA'.
'in' acts as a link.
(Other definitions for guatemala that I've seen before include "place overseas" , "Republic in Central America" , "Central American state" , "Central American country" , "country south of the USA" .)