That is a bleached Entacmaea quadricolor, bulb tip. Your lighting should be fine for that species. Bleached refers to the anemone having lost most/all of its zooxanthellae (algae that colonize the tissue and provide the bulk of that species nutritional needs). Expect that over the weeks and months the anemone will develop a rich brown color. This is a good sign and indicates the overall health of the anemone is improving. Providing the anemone with very good water quality in the mean time will also improve the anemones health. I would try to feed the anemone small (pea size) pieces of fresh seafood--such as fresh shrimp from the seafood dept. of the grocery, also squid, mysis, silversides, krill would be accepted. Target feeding an anemone that is bleached provides it with nutrition that it's lacking due to the absence of the zooxanthellae and also expedites the recolonization of the zooxanthellae because the anemone digesting the food creates food for the algae. The anemone is nicely attached it looks like, which is a good sign. Also, your maroon has its one and only natural anemone host (E. quadricolor). The clown looks about the right size for that size anemone, so all that is good. I would definitely try to get the nitrates down. A nitrate level of 20 won't kill an anemone, but one that's acclimating won't be as happy as it would if the nitrates were lower. In the ocean nitrates are undetectable and that's what I suggest you shoot for. you want your specific gravity in the 1.025-1.026 range, temp in the 78-82F range, moderate water flow. Water changes, protein skimming, good circulation all go a long way toward keeping nitrates down. Also making sure not to overfeed the tank--food is the source of nitrates, ultimately.
To answer your question about anemone hosting if it is dying--I expect your clown would stay with that anemone until death do them part. However, from you pics, I wouldn't expect that anemone to die anytime soon. BTAs are the hardiest of the hosting anemone species and that one looks pretty good (other than being bleached, that is). If it starts to wander, you want to be sure and cover the powerheads. They can be damaged or killed by being sucked into a powerhead intake.