Part of Asia close to Tashkent, for sure (5)
I believe the answer is:
tibet
'part of asia' is the definition.
('Tibet' is part of 'asia')
'close to tashkent for sure' is the wordplay.
'close to' suggests the final letters (the close of something is the end).
'for sure' becomes 'I bet' (both can mean you're unsurprised to hear something).
The final letter of 'tashkent' is 't'.
't'+'ibet'='TIBET'
(Other definitions for tibet that I've seen before include "woollen fabric" , "Chinese region" , "Region of SW China" , "State" , "High place" .)