The BTA is fairly bleached but with propoer care it should recover. It will take some time to color up and regain zooxanthellae. The important question now is what kind of lighting you have over it and how best to acclimate it to those lights. Most suggest using several layers of window screen over the tank and removing a layer every week or 2 until the nem is finally under full lighting. If you have dimmable LEDs, you can go that route. Other options are to reduce the light cycle to just a few hours and slowly increase it. Adjustments to lighting need to take into account the impact to coral health (see you have a few). Note that these acclimation timeframes are suggested for healthy nems so with your being bleached, it may take a little longer.
I wouldn't feed the nem for at least a couple of weeks and when you do feed it, provide it with small foods such as mysis or shreded fresh seafood. The other concern is that clowns may be too hard on the nem in its fragile state which may be another reason its hiding.
Looks like you have several demading animals in there (flame scallop, orange linkia star and what looks like a non-photosynthetic tube anemone).