Taciturn guy’s unexpected story about East (6)
I believe the answer is:
oyster
'taciturn guy's' is the definition.
(oyster can mean a shy or reserved person)
'unexpected story about east' is the wordplay.
'unexpected' is an anagram indicator.
'about' is an insertion indicator.
'east' becomes 'e' (synonyms).
'story' anagrammed gives 'oystr'.
'oystr' enclosing 'e' is 'OYSTER'.
(Other definitions for oyster that I've seen before include "Pearl-generating bivalve" , "Secretive person; bivalve" , "The world of Shakespeare" , "Shellfish (maybe the world!)" , "Pearl container?" .)