The crown of madness spell states:
The charmed target must use its action before moving on each of its turns to make a melee attack against a creature other than itself that you mentally choose...
I am unsure whether this is its own unique action that the spell forces you to make, similar to how class features which "use your action" are their own unique actions. Or if an affected creature can take any action so long as it includes a melee attack.
For example the sections on "Grappling" and "Shoving a Creature" state:
[Y]ou can use the Attack action to make a special melee attack, a grapple...
Using the Attack action, you can make a special melee attack to shove a creature...
Grapple/Shove require specific actions but involve making a melee attack so my question is this:
If you are under the effects of crown of madness, can make a grapple/shove by taking the Attack action, or is it the case that the attack the spell requires is its own, unique action?