Finish in undergarment and neckwear? (8)
I believe the answer is:
pendants
'neckwear?' is the definition.
'finish in undergarment' is the wordplay.
'finish' becomes 'end' (synonyms).
'in' means one lot of letters goes inside another.
'undergarment' becomes 'pants' (pants is a kind of undergarment).
'end' put inside 'pants' is 'PENDANTS'.
'and' acts as a link.
(Other definitions for pendants that I've seen before include "They hang around the neck" , "Hanging ornaments, often on necklace" , "Items of jewellery" , "Bits of jewellery" .)