There's no single-filter panacea for this. It's fundamentally difficult because you can't isolate echo or reverb by frequency. You might find it next to impossible to get satisfactory results in post, and if it matters it'd be better to reshoot or ADR it.
But if you want to attempt it you could try the Noise Gate filter in FCP to cut the echo/reverb trails, and Channel EQ in Soundtrack to roll off low frequencies (if they're a problem). If any of this works, the audio you're left with will not be pretty and you'll have to try to disguise that with atmos and music.
I know this is said about almost everything, but this really does depend on the specifics. Before you try the above I'd recommend posting a sample on a hardcore audio forum and accepting defeat if they tell you it's not going to work.