Twist in the coil is out of the stone age (9)
I believe the answer is:
neolithic
'the stone age' is the definition.
(I've seen this before)
'twist in the coil' is the wordplay.
'twist' indicates anagramming the letters (a twisted or distorted version of the letters).
'in'+'the'+'coil'='inthecoil'
'inthecoil' is an anagram of 'NEOLITHIC'.
'is out of' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for neolithic that I've seen before include "Relating to the later Stone Age" , "Of the later part of the Stone Age" , "Belonging to late Stone Age" , "Stone-Age" , "Description of old age" .)