Rosemary, for example, in feather boa (4)
I believe the answer is:
herb
'rosemary' is the definition.
(thesaurus)
'in feather boa' is the wordplay.
'in' indicates the answer is hidden within the clue.
'HERB' is hidden within 'feather boa'.
'for example' is the link.
(Other definitions for herb that I've seen before include "Plant with leaves or seeds used medicinally" , "Parsley, for instance" , "Basil, for example, is one" , "man's name" , "Chives or coriander, say" .)