red akali move trigger killing single creature in a battlefield but the battlefield has a hidden card, can I target akali

Yes — nothing stops you. Akali, Deadly Weapon (Fury) has no "can't be chosen" clause, so she's an ordinary legal target, and a card played from facedown just has to pick its targets from among options at that battlefield (Rule 811.1.d.2) — which she now is. Hidden cards also gain Reaction while facedown, so you can play it in response to the move trigger.

Two caveats. If the hidden card was hidden at a different battlefield, it can't reach her. And killing her in response doesn't stop the trigger — the 1 (or 2 if Empowered) damage still lands on the chosen unit, since the battlefield she moved to/from is locked in at trigger time (FAQ #11760).

(By contrast, if this were Akali, Silent — the Calm one — she'd be unchoosable unless she were actually in combat, which a move-only showdown won't make her.)