Not joseki  

After the high approach , is unusual in professional play but playable (according to KataGo).

The situation is identical to a 3-4 point low approach kick

can also be played at a or b, White will play an extension at or play elsewhere.

Known result  

This is a known result with GoBase showing 35 hits for this pattern. Comparing this diagram to the original diagram at the top of the page, we see that Black has played an additional stone at and the Black stone is at the location marked by a square rather than at a.

Cut  

If , thenhe natural cut through the keima is a severe potential for Black.

How white should play, cont'd  

Like this, white captures the corner stones.

Making White Heavy  

Black can play this way when / cause White to be heavy in this area.

White is however unlikely to oblige with .

See also 3-4 Point Low Approach Two Space Low Pincer Tenuki #diag8