Gathered to bring in silver (new) that’s attractive (6)
I believe the answer is:
magnet
'that's attractive' is the definition.
'gathered to bring in silver new' is the wordplay.
'gathered' becomes 'met' ('meet' can be a synonym of 'gather').
'to bring in' is an insertion indicator.
'silver' becomes 'ag' ('Ag' can be a synonym of 'silver').
'new' becomes 'n'.
'ag'+'n'='agn'
'met' placed around 'agn' is 'MAGNET'.
(Other definitions for magnet that I've seen before include "Something attractive" , "Attractive item" , "It has the power to attract iron" , "Old comic" , "Attractive piece of metal" .)