Spare silver collected in pool (6)
I believe the answer is:
meagre
'spare' is the definition.
('meagre' can be similar in meaning to 'spare')
'silver collected in pool' is the wordplay.
'silver' becomes 'ag' (Ag is the chemical symbol for silver).
'collected' means one lot of letters goes inside another.
'in pool' becomes 'mere' (mere is a kind of pool. I am not sure about the 'in' bit.**).
'ag' inserted into 'mere' is 'MEAGRE'.
Can you help me to learn more?
(Other definitions for meagre that I've seen before include "Stingy - thin" , "Lacking in quantity/quality" , "skinny" , "Scanty in amount - puts me in rage" , "Skimpy and scarce" .)