Airline once located centrally in country (6)
I believe the answer is:
panama
'country' is the definition.
(Panama is an example)
'airline once located centrally' is the wordplay.
'airline once' becomes 'panam' (Pan Am, short for Pan American World Airways).
'centrally' indicates the central letters.
The central letter of 'located' is 'a'.
'panam'+'a'='PANAMA'
'in' acts as a link.
(Other definitions for panama that I've seen before include "Country - hat - canal - cigar" , "Headgear for a canal" , "isthmus" , "city" , "country divided by boaters?" .)