Blurt tune out, being tempestuous (9)
I believe the answer is:
turbulent
'tempestuous' is the definition.
(I've seen this before)
'blurt tune out' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'blurt'+'tune'='blurttune'
'blurttune' with letters rearranged gives 'TURBULENT'.
'being' acts as a link.
(Other definitions for turbulent that I've seen before include "Violently disturbed" , "Wild, unruly" , "Stormy" , "like Becket?" , "Tumultuous" .)