Language, probably Turkish, in extreme instances acceptable (6)
I believe the answer is:
python
'language' is the definition.
(python is a programming language)
'probably turkish in extreme instances acceptable' is the wordplay.
I cannot quite see how this works, but
'acceptable' could be 'on' (as opposed to not on, unacceptable) and 'on' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for python that I've seen before include "Large non-venomous snake" , "Heavy-bodied snake" , "Large tropical snake that crushes its prey" , "Large snake that crushes and swallows its prey" , "Type of snake" .)