Prickly shrub took an upward course (4)

I believe the answer is:

rose

I'm a little stuck... Click here to teach me more about this clue!

'prickly shrub' is the definition.
(I've seen this before)

'took an upward course' is the wordplay.
'took' becomes 'sor' (I can't justify this - if you can you should give a lot more credence to this answer).
'an upward' is a reversal indicator (in a down clue, letters go up).
'course' becomes 'e'.
'sor' reversed gives 'ros'.
'ros'+'e'='ROSE'

Can you help me to learn more?

(Other definitions for rose that I've seen before include "increased in price" , "Herb - girl's name(s)" , "Popular flower" , "Pink wine - flower" , "Garden flower" .)

I've seen this clue in The Independent.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.