Poet's change of position (6)
I believe the answer is:
motion
I believe this clue is a double definition.
'poet's' is the first definition.
(I've seen this in other clues)
'change of position' is the second definition.
('motion' can be a synonym of 'change of position')
(Other definitions for motion that I've seen before include "Changing state, moving" , "Proposal for discussion or a vote" , "Movement or proposal" , "Old coin of Germany" , "Proposal to be voted on" .)