Chosen to sit after standing (7)
I believe the answer is:
elected
'chosen' is the definition.
(electing is a kind of choosing)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for elected that I've seen before include "Chose by poll" , "Chosen to form government" , "Chosen for office" , "In a position" , "made a choice" .)