Guardian prize

[catsrcool]

9ac Rose proves less than coherent speaker (7) ??M?L?R MUMBLER or RAMBLER? 12ac Bitter (twisted) about exile's old car (7) ??A?A?T 25ac Shed is en voyage in colour (7) I?I?I?E IRIDISE or IRIDIZE prefer the first but can't parse it.

[sandyRoe]

rambler. as in rambling rose?

[dannyk13]

Rambler ( rambling rose)

[cathfromsaron]

teacart

[slaney]

12a Tra(ban)t - old East German car. Anagram of tart around ban(exile)

[dannyk13]

12a. Travant

[dannyk13]

Sorry another typo Trabant

[factor-fiction]

I can see IS in RIDE but can't see where the other I comes from.
IRIDISE seems the more likely

[roslyn251254]

SHED is the compiler today so the extra I would mean himself

[merrythought]

Shed is the compiler therefore : I RIDE containing IS

[shooty]

shed = rid
is = is
en = within (inside) IE
IE = International exploration (Christopher Columbus)

[factor-fiction]

Thanks roslyn- that explains it. IRIDISE it is, then.

[catsrcool]

Thank you all

[shooty]

sorry about my feeble attempt, i should have refreshed before posting : /

[factor-fiction]

Good alternative shooty- I like the is/rid explanation but I don't understand the IE explanation

[tatton7]

I (shed) IS inside RIDE = IRIDISE