Hi-fi using disc before case of tapes turned up (6)
I believe the answer is:
stereo
'hi-fi' is the definition.
(I've seen this before)
'disc before case of tapes turned up' is the wordplay.
'disc' becomes 'O' (disc-shaped letter).
'before' becomes 'ere' (poetic term).
'case of' means to remove the middle letters (outsides of).
'turned up' is a reversal indicator.
'tapes' with its centre removed is 'ts'.
'o'+'ere'+'ts'='oerets'
'oerets' back-to-front is 'STEREO'.
'using' is the link.
(Other definitions for stereo that I've seen before include "Music-playing equipment giving depth of sound" , "Twin-channel sound" , "When sound comes through two channels" , "Of sound equipment, having two speakers" , "Music system with two speakers" .)