Possible Clues:

• Part of the brain
• The optic nerve emerges from this part of the midbrain
• The Alamo, USA, most of all a vital relay station
• Either of the two contiguous egg-shaped masses of grey matter at the base of the brain
• So a clock is placed in part of the brain
• Poirot finally getting computer endlessly to entertain his little grey cells
• Part of brain in this way split by a punch?
• Part of the midbrain where the optic nerve emerges
• Grey matter at base of brain
• So to comprehend lama's reincarnation needs a bit of brain