[M. Thatcher]

Mindedly is not a word. Perhaps you need to pick a field whose lexicon you have the capacity to employ.

[Rudder]

Well, nevertheless, you get the point, don't you?

[aruanan]

Mindedly is not a word. Perhaps you need to pick a field whose lexicon you have the capacity to employ.

On its own, perhaps not, but the meaning of the sentence "He pursued his goal single-mindedly" is exactly equivalent to "He pursued his goal with single-mindedness" and "He was single-minded in the pursuit of his goal". In the first instance "single-minded" is used as an adverb; in the second, as a noun in a prepositional phrase; and in the third, as an adjective. All three are grammatically correct