The poem sets two small scenes side by side and lets the reader work out the link. In the first, a wing is left for a fox to eat. The speaker calls this "how necessary a use," which sounds almost like a dry remark about nature: the wing has a clear purpose, feeding a hungry animal. Nothing is wasted, and nothing needs explaining.
Then comes the turn. Art, the speaker says, is "unlike" this. It sits "in a burrow / of an office," a hidden, cramped place that echoes the fox's den but belongs to desks and paperwork. The title, "Unofficial," hints that the speaker's creative work happens off the books, outside any official role.
The feeling seems wry and a little wistful. The speaker may be wondering whether art is useful in the plain way a meal is, or just something tucked away in a corner of the working day. The mood is quiet, spare and slightly self-mocking, and the short lines leave a lot of room for the reader's own guess.