Clue: More paintings by Emin initially put up (5)
Answer: EXTRA
Explanation: Definition: More 
 **Reversal of**(… put up, in a down clue) [ ART(of which paintings are an example) + X(symbol for mathematical multiplication/by, as in "2 by 2 = 4") + **1st letter of**(… initially) "Emin" ].
And Tracey Emin is a British artist.