Can I legally use this on a space that a character is using an object as hindering terrain?

Quoting the power helps.

Underground Geyser: Give Aquaman a double power action
and choose any square of clear terrain within a range of 8 and line
of fire. Place a special terrain marker in the chosen square and it
becomes water terrain for the rest of the game. Deal a character
occupying that square 3 damage, and then each character
occupying an adjacent square is knocked back from the chosen
square 3 squares.

Squares with an object in them are hindering terrain, not clear terrain, so you cannot choose that square.

Please quote the game effect in question so that we are all on the same page:

Underground Geyser: Give Aquaman a double power action and choose any square of clear terrain within a range of 8 and line of fire. Place a special terrain marker in the chosen square and it becomes water terrain for the rest of the game. Deal a character
occupying that square 3 damage, and then each character occupying an adjacent square is knocked back from the chosen square 3 squares.

Checking page 19 of the rule book shows us:

OBJECTS AS TERRAIN
A square containing an object not held by a character is hindering terrain.

Hindering terrain is not clear terrain, so Aquaman can't use his power in a square with an object.

TK the object away, or destroy it... problem solved... It is very effective against night crawler... not that I would ever do that, oh wait I did.

You say that like Nightcrawler is some sort of threat

one question:

the power ignores super senses or all power to evade block in the dial ( white lantern power) to ask an atk to trigger?

Super Senses requires an attack to activate and this is not an attack.

I don't understand the other part of your question.

this power:
LIVE!: Bart Allen can use Regeneration. When turning the dial, if this click is revealed due to damage taken from an opponent's attack, stop turning the dial.

Underground Geyser is not an attack.