Supplement that’s sometimes removed by The Lancet? (8)
I believe the answer is:
appendix
'supplement' is the definition.
(synonyms)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for appendix that I've seen before include "Supplementary material at the back" , "Writer's addition - may be taken out in the theatre!" , "Supplementary part" , "part of book" , "It contains supplementary material" .)