Yeah, Clindamycin is nasty.
Well, the first thing I would try is some grenadine. It is a pomegranate flavored syrup that is the reason Cosmopolitans are pink. Any place that sells liquor will have it. It is NOT alcoholic. Rose's is the big brand and it is about $3.99 for a bottle. They sell super expensive stuff that is actual cooked down pomegranate syrup - Rose's is artificially flavored and perfect for this.
Pour a tiny bit in a dish or bottle cap. Get your meds all measured up in the syringe - so you have that liquid up to the 0.4ml line. Then, place the tip of the syringe in the grenadine and pull up at least an equal amount - that would be up to 0.8ml.
Now, when you stick the syringe in the mouth the first thing the squirrel will taste is the grenadine, which they like.
It ***MIGHT*** help.
She isn't going to come up and eat it on her own, you are probably going to have to do some "handling." to accomplish this.