A fellow possibly aghast in new country (11)
I believe the answer is:
afghanistan
'country' is the definition.
(Afghanistan is an example)
'a fellow possibly aghast in new' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'possibly' indicates anagramming the letters.
'new' becomes 'n' (**).
'aghast'+'in'='aghastin'
'aghastin' anagrammed gives 'ghanista'.
'a'+'f'+'ghanista'+'n'='AFGHANISTAN'
(Other definitions for afghanistan that I've seen before include "Country with capital Kabul" , "republic" , "dangerous country" , "This type of country" , "Landlocked Asian country" .)