Bad painting taking in north European river (6)
I believe the answer is:
danube
'river' is the definition.
(Danube is an example)
'bad painting taking in north european' is the wordplay.
'bad painting' becomes 'daub' (term for an unprofessional painting).
'taking in' indicates putting letters inside.
'north' becomes 'n' (synonyms).
'european' becomes 'e' (abbreviation e.g. EU).
'daub' enclosing 'n' is 'danub'.
'danub'+'e'='DANUBE'
(Other definitions for danube that I've seen before include "It's blue according to the song" , "Ban due (anag) - river" , "Great European river, musically blue (6)" , "River flowing from Black Forest to Black Sea" , "5 down's river" .)