Flag art displayed with artist in London square (9)
I believe the answer is:
trafalgar
'square' is the definition.
(I've seen this before)
'flag art displayed with artist in london' is the wordplay.
I cannot really see how this works, but
an anagram of 'flag' is 'falg' which is present in the answer.
an anagram of 'art' is 'tra' which is present in the answer.
The remaining letters 'ar' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for trafalgar that I've seen before include "Battle won by Nelson in 1805" , "Eighteen zero five naval battle" , "1805 sea battle" , "1805 naval battle" , "British naval victory" .)