Sort of rock group: it's one not electrified, since unplugging leads surprisingly (7)
I believe the answer is:
igneous
'sort of rock' is the definition.
'it's one not electrified since unplugging leads surprisingly' is the wordplay.
'it's' becomes 'ig' (I can't justify this - if you can you should believe this answer much more).
'leads' suggests taking the first letters.
'surprisingly' indicates anagramming the letters.
The initial letters of 'one not electrified since unplugging' is 'onesu'.
'onesu' with letters rearranged gives 'neous'.
'ig'+'neous'='IGNEOUS'
'group' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for igneous that I've seen before include "(Of rocks) formed from lava or magma" , "Originally molten (rock)" , "Type of rock with molten origin" , "Category of rock, being of solidified molten magma" , "(Of rock) solidified from lava or magma" .)