Beryl from south-east, gaining weight? (5)
I believe the answer is:
stone
'beryl' is the definition.
(thesaurus)
'south-east gaining weight?' is the wordplay.
'south east' becomes 'SE' (abbreviation).
'gaining' means one lot of letters goes inside another.
'weight?' becomes 'ton' (unit of weight).
'se' placed around 'ton' is 'STONE'.
'from' is the link.
(Other definitions for stone that I've seen before include "14 lb" , "Hard lump of mineral matter" , "Olive pip" , "See 1" , "Beryl, ruby" .)