Old boy rolling India's rock (8)
I believe the answer is:
obsidian
'rock' is the definition.
(obsidian is a kind of rock)
'old boy rolling india's' is the wordplay.
'old boy' becomes 'ob'.
'rolling' is an anagram indicator.
'indias' with letters rearranged gives 'sidian'.
'ob'+'sidian'='OBSIDIAN'
(Other definitions for obsidian that I've seen before include "A hard black volcanic glass" , "Dark volcanic glass" , "A glassy volcanic rock" , "Glass bottle may be in this" , "Dark glassy rock formed from lava" .)