What should be the referee's call?

Here's the scenario....

The ball is played forward but the receiving player is offside, the linesman waves his flag for it, but before the whistle is blown the nearest defender tackles and fouls the offside player. Which call would take priority? Would the defending team get the free kick for the offside, or the attacking team get it for the foul? Would the severity of the challenge effect the decision over which call to make?

Once the whistle is blown for offside the game has been stopped and the ball is technically not in play.
The tackle would then come under ungentlemanly conduct and be dealt with accordingly.

Some haven麓t read the question properly,the game hadn麓t officially been stopped as stated by some.

The first would get precedent the second, depending on severity would either get a caution or worse. It麓s up to the ref.

The first infraction would stand, the defender who committed the foul could not be held responsible as the whistle had not yet been blown, he may get a talking to and whatnot but i don't believe the ref can book him or etc.