Case of doctor holding 50% of ribose for pharmacist? (5)

'pharmacist?' is the definition.
I don't know anything about this answer so I can't tell whether this works.

'case of doctor holding 50% of ribose' is the wordplay.
'case of' means to remove the middle letters (like emptying a case).
'holding' indicates putting letters inside.
'50% of' indicates taking half.
'doctor' with its centre taken out is 'dr'.
'ribose' with half the letters taken is 'ose'.
'dr' enclosing 'ose' is 'DOSER'.

'for' acts as a link.

Can you help me to learn more?