How the treatment is working if the patient feels quite ill? (6,6)

I believe the answer is:

rather poorly

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

'how the treatment is working if the patient feels' is the definition.
I can't judge whether this defines the answer.

'quite ill?' is the wordplay.
'quite' becomes 'rather' (synonyms).
'ill?' becomes 'poorly' ('poorly' can be similar in meaning to 'ill').
'rather'+'poorly'='RATHER POORLY'

Can you help me to learn more?

Want a hint initially instead of a full solution? Install my app