Is it the one in brown who's the artist? (6)
I believe the answer is:
titian
'the artist?' is the definition.
(16th-century painter)
'is it the one in brown' is the wordplay.
I cannot really see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
'is' could be 'ii' (more than one I) and 'ii' is present in the remaining letters.
'one' could be 'an' (an apple is one apple) and 'an' is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'who's' acts as a link.
Can you help me to learn more?
(Other definitions for titian that I've seen before include "Sixteenth century Venetian painter" , "artist from Venice" , "Venetian Renaissance painter" , "Venetian old master, d. 1575" , "Venetian painter - shade of red" .)