There are a number of ways for a group to end up under the power of an enemy or adversary. If the group survives such a situation at all, it seems very reasonable to expect said enemy to imprison the group and remove all equipment to reduce their ability to threaten their captor.
If my group finds themselves in this situation, how should I balance combat encounters effectively for this? Is there a good rule of thumb for such a situation? Should I avoid triggering a combat encounter until the group has an opportunity to equip themselves? I like the idea of subjecting the group to a challenge against opponents that would normally seem trivial, but if it's difficult to achieve reliably I'd prefer to steer clear.
I am looking at this from the perspective of “you break out of your confinement, but fail to sneak past whoever is guarding you, fail to persuade/intimidate/bribe etc, and combat is now inevitable”. I can of course make combat not inevitable if necessary, but it seems like a natural result and an interesting challenge to overcome.
I have a sorcerer, fighter, druid, ranger, cleric and paladin in the group.
Is there any effective way to balance a combat encounter for 6 level 4 players who have no equipment?