noun, na-adjective, noun which may take the genitive case particle 'no'
devoted to work; workaholic; single-mindedly focused on one's job
Describes a person who is completely absorbed in their work, often to the exclusion of other interests. Can be used as a noun or adjectivally with な or の.
He is so devoted to his work that he is at the office even on most holidays.
If you lead a workaholic life, you end up with less time for your family.
仕事人間 is a more common and slightly more colloquial term for a workaholic, while 仕事一途 emphasizes single-minded devotion and can sound more literary or formal.
一途 alone means 'single-minded' or 'earnest' and can be used for various passions, not just work. 仕事一途 specifically narrows the focus to work.
Compound of 仕事 (work) and 一途 (single-minded, earnest). The exact historical derivation is uncertain, but the combination straightforwardly conveys 'devoted solely to work'.