The creative midfielder is out of contract in the summer and will turn 34 in October.
"I am absolutely adamant he has to stay at the club."
Wenger added: "When he arrived here he was less a tactical player and more the 'Mozart from Prague' and he was purely creative, offensive player.
"Today he is a real organiser on the pitch as well. I like to have him in the team because he gives a real structure to our team."
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