You're right, physio helped my posture (1,5,9)
I believe the answer is:
i stand corrected
'you're right' is the definition.
The definition suggests an adjective which matches the answer.
'physio helped my posture' is the wordplay.
I cannot quite understand how this works, but
'my' could be 'cor' (both are expressions of surprise) and 'cor' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for i stand corrected that I've seen before include "Oops!" , "I'll give you that" .)