Popular recording grabbing one, volume is turned up (7)
I believe the answer is:
Here is my best explanation:
'popular' is the definition.
'recording grabbing one volume is turned up' is the wordplay.
'recording' becomes 'cid' (I can't explain this - if you can you should believe this answer much more).
'grabbing' means one lot of letters goes inside another.
'one volume' becomes 'tome' (I've seen this before).
'is turned up' is a reversal indicator.
'cid' placed around 'tome' is 'citomed'.
'citomed' in reverse letter order is 'DEMOTIC'.