Christmas stocking originally bought for chemist (5)
I believe the answer is:
nobel
'chemist' is the definition.
(I know this)
'christmas stocking originally bought' is the wordplay.
'christmas' becomes 'noel' (synonyms).
'stocking' indicates putting letters inside ('stock' can mean 'carry' or 'contain').
'originally' suggests taking the first letters.
The first letter of 'bought' is 'b'.
'noel' enclosing 'b' is 'NOBEL'.
'for' is the link.
(Other definitions for nobel that I've seen before include "Dynamite inventor, Prize founder" , "he provided prizes" , "-- Peace Prize" , "Alfred --, international prize founder" , "Philanthropic Swede noted for establishing international prizes" .)