Ring contains right gem (5)
I believe the answer is:
pearl
'gem' is the definition.
(I know that pearl is a type of gem)
'ring contains right' is the wordplay.
'ring' becomes 'peal' (pealing is a kind of ringing).
'contains' is an insertion indicator.
'right' becomes 'r' (abbreviation).
'peal' going around 'r' is 'PEARL'.
(Other definitions for pearl that I've seen before include "See 12" , "something highly valued" , "Much loved and valued person" , "Off-white colour" , "Paragon" .)