Having been trounced, alas, not in major papers (9)
I believe the answer is:
nationals
'major papers' is the definition.
(newspapers with national circulation)
'having been trounced alas not in' is the wordplay.
'having been trounced' indicates anagramming the letters (letters trounced or beaten).
'alas'+'not'+'in'='alasnotin'
'alasnotin' anagrammed gives 'NATIONALS'.
(Other definitions for nationals that I've seen before include "citizens" , "Stan, a lion (anag.)" , "newspapers" , "countrymen" , "Country folk" .)