Vitamins taken, it's noted (9)
I believe the answer is:
acclaimed
'noted' is the definition.
(both can mean famous or celebrated)
'vitamins taken' is the wordplay.
I cannot quite understand how this works, but
'taken' could be 'claimed' ('claim' can be a synonym of 'take') and 'claimed' is found within the answer.
The remaining letters 'ac' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'it's' acts as a link.
Can you help me to learn more?
(Other definitions for acclaimed that I've seen before include "Hailed, heralded" , "Highly respected" , "Strongly praised" .)