Be captivated by songbird in this region (5)
I believe the answer is:
tibet
'this region' is the definition.
(Tibet is a region in Asia)
'be captivated by songbird' is the wordplay.
'captivated by' indicates putting letters inside.
'songbird' becomes 'tit' (tit is a type of songbird).
'be' put into 'tit' is 'TIBET'.
'in' acts as a link.
(Other definitions for tibet that I've seen before include "region out East" , "Mountainous Asian region" , "High place" , "Asian location" , "Himalayan region controlled by China" .)