Wenger said: "It is down to the chairman and to the board. Personally I am not in favour of it but if the chairman wants that and if the club agrees... I always tried to keep my contracts not involved in these kind of clauses as it can be misinterpreted - and I never wanted that."
Aston Villa boss Gerard Houllier was 'surprised' to hear Holloway stands to cash in on any Adam deal.
He has had a war of words with Ollie over a failed bid for the playmaker.
And he said: "I don't know if it's legal or illegal.
"It is surprising but it is their business, not mine."