Precious stone Margaret recalled (3)
I believe the answer is:
gem
'precious stone' is the definition.
(gem is a kind of precious stone)
'margaret recalled' is the wordplay.
'margaret' becomes 'meg'.
'recalled' shows that the letters should be reversed in order.
'meg' backwards is 'GEM'.
(Other definitions for gem that I've seen before include "Half of 7 [SIGN OF THE ZODIAC]" , "A jewel or precious stone" , "A precious stone like a diamond or emerald etc" , "perfect specimen" , "Valuable stone" .)