To clarify: the enemy is presumably hoping you will place your guys right at the front edge of the built-up zone so that you have a clear field of fire as he approaches. He will then identify your positions and drench them with artillery and direct fire. This essentially negates much of the advantage of defending the city and turns it into a ranged fight with one side hiding in concrete – an advantage, but not as big an advantage as a real in-depth city defense. With luck he will be able to concentrate on your strength and degrade or destroy it while it sits where he can see it and pound it.
Your objective is not to play that game. Put your hedgehogs back inside the built-up zone so he can’t see you positions without having to go into the town and get tangled up in your deadly embrace. Use the scouting forces to lightly occupy the frontal edges of the built-up area to detect and monitor his approach without exposing your main strength to bombardment.
He will have to enter the maze to take it. If he dilutes his strength you can try to concentrate and fall on separated units; if he stays in a strong column, it will have flanks. Use buildings as a screen to manuever to attack the flanks. Buildings he occupies with strong infantry you can bring tanks against and shell, if you can avoid taking much return fire; otherwise hold your tanks back to stab at the flanks of his column.
Your tanks can, in theory, fight face to face against enemy tanks, but why fight fair? Smash infantry that doesn’t have tanks from a safe range, then back away to safety; hit enemy tanks in their weak flanks as they deploy to smash YOUR hedgehogs.
Again, this is theory; practice is…messier.
