Mephisto 2545

[Totterdown]

I would be grateful for help with three clues.

7a - Where's Italian conciliator? (4) ?OV?

7d - Old copper coin held up - as, in fact (5) ?ATU?
Could this be datum?

3d - Struggle, entering competition to support festival, to find how something natural may be structured (12)
T?TR?GO?ALLY. I can only find tetragonally, but cannot see how the letters fit with the wordplay.

Thanks for any help.

[Ardboe]

7a dove

[Ardboe]

forgot to add - tetragonally is correct
Tet(festival)r(agon)ally

[Totterdown]

Thanks Ardboe. I assume 7d must be datum?

[kayakamina]

Yes Datum

[Rollo]

An old copper coin = DAM

As = UT

So, ut backwards (held up) in dam

[Totterdown]

Thank you all. I thought it must be datum but could not work it out. So thanks Rollo, you clever old thing!