Rock band is unsettled touring India following row essentially (8)
I believe the answer is:
'rock' is the definition.
(I know that obsidian is a type of volcanic glass)
'band is unsettled touring india following row essentially' is the wordplay.
'unsettled' indicates anagramming the letters.
'touring' indicates putting letters inside (touring can mean going round).
'india' becomes 'i' (phonetic alphabet: alpha, bravo, charlie etc.).
'following' is a charade indicator (letters next to each other).
'row essentially' becomes 'o' (I can't explain this - if you can you should give a lot more credence to this answer).
'bandis' with letters rearranged gives 'bsidan'.
'bsidan' going around 'i' is 'bsidian'.
'bsidian' after 'o' is 'OBSIDIAN'.
Can you help me to learn more?
(Other definitions for obsidian that I've seen before include "A glassy volcanic rock" , "Dark volcanic glass" , "Glass bottle may be in this" , "Dark glassy rock formed from lava" , "Dark volcanic rock" .)