Court case regarding family putting out book (5)
I believe the answer is:
trial
'court case' is the definition.
(a trial in court)
'family putting out book' is the wordplay.
'family' becomes 'tribal' (both can mean relating to one's family).
'putting out' indicates named letters should be taken away.
'book' becomes 'b' (abbreviation for book).
'tribal' with 'b' removed is 'TRIAL'.
'regarding' is the link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for trial that I've seen before include "Testing, experiment" , "Ordeal or lawsuit" , "Judicial hearing and judgment" , "pain in the neck" , "Proceedings to determine guilt or innocence" .)