Showed tiredness or boredom (6)
I believe the answer is:
yawned
'showed tiredness or boredom' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for yawned that I've seen before include "Showed tiredness or tedium" , "Showed tiredness or boredom" , "Opened mouth wide as expression of boredom" , "Gave visible sign of boredom - or tiredness" , "Breathed deeply with mouth wide open" .)