"fond" meaning a small quantity

[alan gould]

is this a common usage:

Il ne lui restait qu'un fond de vin rouge.      He only had a drop of red wine left. 

[Sandra]

Yep !

le fond = the bottom

"un fond de [+ liquid]" implies that you have just enough left to covert the bottom of the more adequate recipient .

For wine, we suppose it's a glass or a bottle....

We also use :

"il ne lui restait qu'une goutte de vin rouge" 

"goutte" is the literal translation of "a drop" but here it's not an expression in French, when you use "goutte" you really mean a drop, or a teaspoon at maximum.