Pithy saying upset an old Turkish person (7)
I believe the answer is:
ottoman
'old turkish person' is the definition.
(as in the Ottoman Empire)
'pithy saying upset an' is the wordplay.
'pithy saying' becomes 'motto' (a motto is a saying or slogan).
'upset' shows that the letters should be reversed in order.
'motto' reversed gives 'ottom'.
'ottom'+'an'='OTTOMAN'
(Other definitions for ottoman that I've seen before include "Description of empire" , "item of furniture" , "Low upholstered seat - relating to a Turkish dynasty" , "Turkish empire or ling cushioned seat" , "Armless, padded seat" .)