Penny found by Europeans, six, quiet and irritable (7)
I believe the answer is:
peevish
'irritable' is the definition.
(I know that irritable can be written as peevish)
'penny found by europeans six quiet' is the wordplay.
'penny' becomes 'p' (short for pence).
'found by' is a charade indicator (letters next to each other).
'europeans' becomes 'ee' (an abbreviation for European written twice).
'six' becomes 'VI' (Roman numerals).
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'p'+'ee'+'vi'+'sh'='PEEVISH'
'and' is the link.
(Other definitions for peevish that I've seen before include "Spiteful" , "In irritable state" , "Cranky, easily annoyed" , "Easily irritated or annoyed" , "Fractious" .)