Base silver starts shining (5)
I believe the answer is:
aglow
'shining' is the definition.
(I've seen this before)
'base silver starts' is the wordplay.
'base' becomes 'low' ('low' can be a synonym of 'base'**).
'silver' becomes 'ag' ('Ag' can be a synonym of 'silver').
'starts' says to put letters next to each other.
'low' put after 'ag' is 'AGLOW'.
(Other definitions for aglow that I've seen before include "Lit up" , "Red-hot" , "Incandescent" , "On fire" , "Warm - shiny" .)