A simple silver lining that’s skimpy (6)
I believe the answer is:
meagre
'that's skimpy' is the definition.
(I've seen this before)
'a simple silver lining' is the wordplay.
'a simple' becomes 'mere' (I've seen this in another clue).
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'lining' means one lot of letters goes inside another.
'mere' placed around 'ag' is 'MEAGRE'.
(Other definitions for meagre that I've seen before include "deficient in amount" , "Lean; lacking in quality" , "Lean and scanty" , "Sparse" , "Thin on the ground, scarce" .)