Shining silver base (5)
I believe the answer is:
aglow
'shining' is the definition.
(I've seen this before)
'silver base' is the wordplay.
'silver' becomes 'ag' (Ag is the chemical symbol for silver).
'base' becomes 'low' ('low' can be a synonym of 'base').
'ag'+'low'='AGLOW'
(Other definitions for aglow that I've seen before include "Illuminated" , "On fire" , "Warm - shiny" , "Smouldering" , "Flushed and rosy" .)