Jewellery calls for attention to collar (7)
I believe the answer is:
earring
'jewellery' is the definition.
(earring is a kind of jewellery)
'attention to collar' is the wordplay.
'attention' becomes 'ear' (ear is a kind of attention).
'to collar' becomes 'ring'.
'ear'+'ring'='EARRING'
'calls for' is the link.
(Other definitions for earring that I've seen before include "Ornament on lobe" , "Aural pendant" , "Piece of jewellery" , "Item of jewellery" , "Otic adornment" .)