Instruction from germophobe host? Confess everything! (4,5)
I believe the answer is:
come clean
'confess everything' is the definition.
(to come clean is to confess to a wrongdoing)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for come clean that I've seen before include "how you hope your home delivery laundry will arrive" , "Make honest admission" , "Reveal dirty secrets" , "Admit" , "Confess fully or arrive after ablutions" .)