Supply all pertinent information to lawyer (5)
I believe the answer is:
brief
I believe this clue is a double definition.
'supply all pertinent information to' is the first definition.
(brief can mean to give someone information)
'lawyer' is the second definition.
(I've seen this before)
(Other definitions for brief that I've seen before include "Instructions for barrister" , "Short in duration" , "Remit" , "Terse" , "Case given to a barrister" .)