Protecting recording that's useful to electrician (10,4)
I believe the answer is:
insulating tape
'useful to electrician' is the definition.
I can't judge whether this defines the answer.
'protecting recording' is the wordplay.
'protecting' becomes 'insulating' (insulate can mean to protect).
'recording' becomes 'tape' (tape is a kind of recording).
'insulating'+'tape'='INSULATING TAPE'
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for insulating tape that I've seen before include "Wrap for exposed electric wires" , "sticky strip" , "binder?" .)