An artist took one in (5)
I believe the answer is:
monet
'an artist' is the definition.
(painter Claude Monet)
'took one in' is the wordplay.
'took' becomes 'mt' (I can't justify this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'mt' placed around 'one' is 'MONET'.
Can you help me to learn more?
(Other definitions for monet that I've seen before include "Claude ---, painter (waterlilies)" , "French Impressionist with famous garden" , "Claude --, French impressionist painter" , "Claude -, French artist" , "Claude, impressionist painter, d. 1926" .)