Turn up the volume to penetrate the unresponsive (6)
I believe the answer is:
invert
'turn up' is the definition.
(I've seen this before)
'volume to penetrate the unresponsive' is the wordplay.
'volume' becomes 'v' (abbreviation for volume in book titles).
'to penetrate' means one lot of letters goes inside another.
'the unresponsive' becomes 'inert' (I've seen this in another clue).
'v' going into 'inert' is 'INVERT'.
'the' acts as a link.
(Other definitions for invert that I've seen before include "Turn upside-down" , "Upend" , "Upset" , "Turn upside down, reverse order" , "Turn turtle" .)