Disastrous ruse mostly plating silver (6)
I believe the answer is:
tragic
'disastrous' is the definition.
(thesaurus)
'ruse mostly plating silver' is the wordplay.
'ruse' becomes 'trick' (I've seen this before).
'mostly' means to remove the last letter.
'plating' indicates putting letters inside (I've seen this in other clues).
'silver' becomes 'ag' ('Ag' can be a synonym of 'silver').
'trick' with its last letter taken away is 'tric'.
'tric' enclosing 'ag' is 'TRAGIC'.
(Other definitions for tragic that I've seen before include "Disastrous, appalling" , "Characterised by extreme distress or sorrow" , "Deeply distressing" , "Extremely sad; Mahler's 6th nickname" , "Heart-rending" .)