Possible Clues:

• Bodily organ associated with bad humour
• An irritability we all have lurking inside us
• Bad temper or body organ
• Organ associated with ill humour
• The organ once thought to be the seat of anger
• Viewed about a little plural for ill-humour
• Nonessential organ
• Organ that may be vented
• Organ - that is vented!
• Bad temper as from body organ