Ok I'm going to start this out with this is my opinion and that preds aren't my specialty someone else may know better.
Depends on a few things. If the clam is constantly having things swim by and disturb it at close range it will close and not get any food from either lighting or feeding, so if this happens to much it will obviously starve. So if you want to include one I would recomend putting it in a place that it will be disturbed significantyl less if possible. Oh the other problem is alot of big preds are known for pushing rockwork around so if they deside to throw a fit and knock some rocks onto your 60$+ clam then you wont be happy.
Some Wasses may nip the clam, but that said most Wrasses don't get big enough to be safe with groupers/sharks/rays/eels, and those that do are NOT reef safe as in the will either nip/eat your corals or nip at your clam (depending on the Wrasse veriety).
That also said if its a fish eating eel (as in not "stone tooth") its only a matter of time before the eel is big enough/hungry enough to eat anything you put with them, including sharks and rays... though I feel like those two are not fish eaters... I could be wrong eels aren't my specialty.
Generaly speaking I never put corals or other sensile inverts in with any type of preds... its just not worth the risk to me, as clams and corals are not only expencive but they are living things so I wont risk their lives just to amuse myself lol.
SO in conclution I say probably better not to (for one it will cut costs on your tank hugely as coral maintenance is super expencive lighting alone is rediculus FOWL tank requires light... but you can use generic flouresents for those not expencive T5 or MH setups) as they risk being bumped/knocked over by the big preds or possibly being eaten.