Oliver’s decisive change of direction (5)
I believe the answer is:
twist
This clue is a double definition.
'oliver's' is the first definition.
(I've seen this before)
'decisive change of direction' is the second definition.
(Other definitions for twist that I've seen before include "Spiral" , "Deal card face upwards" , "Wind about; sixties dance" , "Dickens's 'Oliver - - '" , "Writhe" .)