A mineral or tea centre (3)
I believe the answer is:
ore
'a mineral' is the definition.
(ore is a kind of mineral)
'or tea centre' is the wordplay.
'centre' indicates the central letters.
The middle of 'tea' is 'e'.
'or'+'e'='ORE'
(Other definitions for ore that I've seen before include "tangle" , "Mineral - Scandinavian money" , "foreign money" , "Material for smelting" , "Raw mineral" .)