One who breaks down in the lab? A record producer, we hear (7)
I believe the answer is:
analyst
'one who breaks down in the lab?' is the definition.
(someone who breaks down or analyses things)
'a record producer we hear' is the wordplay.
'a record producer' becomes 'annalist' (someone who produces annals).
'we hear' shows a homophone (sound like).
'annalist' is a homophone of 'ANALYST'.
(Other definitions for analyst that I've seen before include "Expert who studies data and recommends appropriate action" , "Examiner - psychiatrist" , "One making detailed study" , "Psychological therapist" , "One examining in detail" .)