Here is a sentence:
Er war groß und bullig und hatte fast keinen Hals, dafür aber einen sehr großen Schnurrbart.
This one is quite confusing to me because I thought that the so called da-adverbs have to be used in cases when the thing they're referring to has already been mentioned. Hence, "dafür" would mean something like "for that". But I do not understand the grammar behind this case in point.