Further curbing acidity in painkiller (8)
I believe the answer is:
morphine
'painkiller' is the definition.
(I know that morphine is a type of painkiller)
'further curbing acidity in' is the wordplay.
I cannot really understand how this works, but
'acidity' could be 'ph' and 'ph' is found within the answer.
'in' is present in the answer.
'further' could be 'more' (synonyms) and 'more' is located in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for morphine that I've seen before include "Opium drug for relieving pain" , "Sedative derived from opium" , "Pain-relieving opiate" , "Pain-killing drug" , "Pain-easing opiate" .)