Just how much is a clove of garlic?

In my cooking 1 clove is about 1/3 of a head, just like Mom, haha.

But really, like the others wrote before me, it's personal taste. I have a friend who can't have alum's so she always skips the garlic & onions. When it comes down to it, that's all cooking it - personal taste. If you don't like raisins, then use cranberries in your oatmeal cookies :)

Agree with general guidelines in what 702551 has written.
Also, there are some common estimates (used so long I forget from where) as used in recipes. Use as a starting point in your prep.
* one garlic clove averages about 1 tsp or 3 cloves make 1 tbsp
* one garlic clove by weight, 3 to 5 grams each

I usually interpret this as a medium size clove from an ordinary supermarket garlic bulb, perhaps the size of a marble.

When there is no special detail provided, it is generally accepted to use commonly available products (like what one would find in a supermarket) rather than assume it is something obscure or unordinary.

That said, you should adjust according to your taste and those who will be joining you at your dinner table.

I'm not a fan of excessive amounts of garlic which can easily overwhelm a dish so I tend to err on the side of less garlic, not more.

But it's entirely up to you.

Best of luck.