Sort that is stored in glasses (7)
I believe the answer is:
species
'sort' is the definition.
(I know that species is a type of sort)
'that is stored in glasses' is the wordplay.
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'stored in' means one lot of letters goes inside another.
'glasses' becomes 'specs' (spectacles).
'ie' inserted inside 'specs' is 'SPECIES'.
(Other definitions for species that I've seen before include "Sort, type" , "Group of organisms" , "Kind, sort" , "Taxonomic group whose members can interbreed" , "Living group; kind" .)