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Yes they can nip and harass clam mantles which will ultimately lead to the clams death if the shrimp is not removed. If you have a refugium you could always house the cleaner their if he picks at it.
There are lots of things like dwarf angles that will peck at clam mantles. I can't keep clams in my main tank as a result of the constant pestering. Even the wrasses will pick at them some times. They won't hurt them, but the constant stress kills the clam.