Bitter substance girl preserved apparently (6)
I believe the answer is:
tannin
'bitter substance' is the definition.
(I've seen this before)
'girl preserved apparently' is the wordplay.
I cannot quite see how this works, but
'girl' could be 'anni' and 'anni' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for tannin that I've seen before include "Something in red wines" , "Compound found in tea, used for dyeing" , "Compound used to convert hide into leather" , "something from tea" , "Bark extract" .)