disarm - psyche

Vamp A acts and does hs 1 in combat, vamp B strikes for hs 3, no presses are played, Vamp A plays psyche; vamp B now wants to play disarm. Is that possible or is psyche still another timing on 'end of round / end of combat'

Yes, It's possible. Link for reference.

The relevant ruling is www.vekn.net/forum/rules-questions/76990-correct-order-impulse-for-combat-cards-after-combat#90516

As Psyche doesn't immediately start the new combat Disarm is playable and would effectively cancel the Psyche combat as vampire A is sent to torpor.