Tea in small bag's secure (8)
I believe the answer is:
purchase
'secure' is the definition.
(thesaurus)
'tea in small bag's' is the wordplay.
'tea' becomes 'cha' (cha is a type of tea).
'in' indicates putting letters inside.
'small bag' becomes 'purse' (I've seen this before).
'cha' placed within 'purse' is 'PURCHASE'.
(Other definitions for purchase that I've seen before include "Spend some money" , "firm grasp" , "Firm grip" , "Procure" , "become an owner" .)