Artist and art returned, having wrong flag for battle (9)
I believe the answer is:
trafalgar
'battle' is the definition.
(Trafalgar is an example)
'artist and art returned having wrong flag' is the wordplay.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'and' says to put letters next to each other.
'returned' is a reversal indicator.
'having' means one lot of letters goes inside another.
'wrong' is an anagram indicator.
'ra'+'art'='raart'
'raart' in reverse letter order is 'traar'.
'flag' is an anagram of 'falg'.
'traar' placed around 'falg' is 'TRAFALGAR'.
'for' acts as a link.
(Other definitions for trafalgar that I've seen before include "Nelson battle and London Square" , "19th century battle" , "Battle won by Nelson in 1805" , "London Square with Nelson column" , "Public space in central London" .)