Using a class ability and discarding the class

[Griffen25]

Example/Question: Can a cleric discard a card and Resurrect an undead creature, start fighting it, discard a following 3 cards to Turn it (gaining +9)
and then discard the cleric card whilst still in combat with the undead monster?

According to the flowchart you can discard/play classes in combat, but does this effect the class abilities that you've already used?