Noticeably beginning to stick one's tongue in Shiraz (5)
I believe the answer is:
farsi
'tongue in shiraz' is the definition.
(Farsi is spoken in Shiraz in Iran)
'noticeably beginning to stick one's' is the wordplay.
'noticeably' becomes 'far' (by far).
'beginning to' suggests taking the first letters.
'one' becomes 'i' (Roman numeral).
The initial letter of 'stick' is 's'.
'far'+'s'+'i'='FARSI'
(Other definitions for farsi that I've seen before include "Iran's official language" , "Iranian language, also widely spoken in Afghanistan" , "Persian language" , "Modern Persian lang." , "foreign language" .)