Guardian 25346

[Aperio]

Mammal from Simon's territory, so we've heard (8) ? S?R?N?A? .Sirenian is a mammal, but I can't see how it fits the rest of the clue

[penelope2]

So we've heard = sounds like. Irenian sounds like iranian = territory, with S (for Simon).

[bibblebub]

biblical reference to Simon the Cyrenian

[Aperio]

Many thanks Penelope & Bibblebub. Both explanations are plausible, but I think the biblical reference is what the compiler had in mind.