Old master dismisses arts produced by Lisa del Giocondo, for one, in the Mona Lisa (5)
I believe the answer is:
model
'by lisa del giocondo for one in the mona lisa' is the definition.
I can't tell whether this definition defines the answer.
'old master dismisses arts' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'master' becomes 'm'.
'dismisses' is an anagram indicator (I've seen 'dismissed' mean this).
'arts' becomes 'del' (I can't explain this - if you can you should believe this answer much more).
'o'+'m'='om'
'om' anagrammed gives 'mo'.
'mo'+'del'='MODEL'
'produced' is the link.
Can you help me to learn more?
(Other definitions for model that I've seen before include "Small-scale version" , "Artist's sitter" , "Moss, say" , "Scale representation" , "A displayer of fashions" .)