Not one book left by European's worthy (5)
I believe the answer is:
noble
'worthy' is the definition.
(synonyms)
'not one book left by european's' is the wordplay.
'not one' becomes 'no' (similar in meaning).
'book' becomes 'b' (abbreviation for book).
'left by' becomes 'l' (I've seen this in other clues).
'european' becomes 'E' (abbreviation e.g. EU).
'no'+'b'+'l'+'e'='NOBLE'
(Other definitions for noble that I've seen before include "Of high rank or birth" , "Of blue blood" , "Possibly count" , "Lord" , "old British coin" .)