Here are a few options:
* An Sionnach Airgid: This is a literal translation, meaning "The Silver Fox." It's straightforward and widely understood.
* An Sionnach Liath: This translates to "The Grey Fox," which might be a more accurate description of a fox's fur color than "silver."
* An Sionnach Sleamhain: This translates to "The Sly Fox," emphasizing the cunning aspect often associated with the term "silver fox." This is a better choice if "silver fox" is used metaphorically to describe a person.
* A Seán na gCeann Liath: This is a more poetic and idiomatic option that might be used for an older, silver-haired person, essentially meaning "John of the Grey Hairs."
The best option depends on the context. If you're talking about an actual fox with silvery fur, *An Sionnach Airgid* or *An Sionnach Liath* are good choices. If you're referring to a cunning person, *An Sionnach Sleamhain* or even *A Seán na gCeann Liath* (depending on gender and desired level of formality) might be more appropriate.