Spies old woman adopting extremes of altogether revolting language ... (7)
I believe the answer is:
aramaic
'language' is the definition.
(I've seen this before)
'spies old woman adopting extremes of altogether revolting' is the wordplay.
'spies' becomes 'cia'.
'old woman' becomes 'ma' (I've seen this in other clues).
'adopting' indicates putting letters inside.
'extremes of' says to hollow out the word (remove centre letters).
'revolting' says the letters should be written backwards.
'altogether' with its middle taken out is 'ar'.
'cia'+'ma'='ciama'
'ciama' going around 'ar' is 'ciamara'.
'ciamara' back-to-front is 'ARAMAIC'.
(Other definitions for aramaic that I've seen before include "tongue" , "Language of Near East" , "Language believed to have been spoken by Jesus" , "Biblical speech" , "Semitic language spoken in New Testament times" .)