Pressure by chief barrister presenting case (7)
I believe the answer is:
pleader
'barrister presenting case' is the definition.
'pressure by chief' is the wordplay.
'pressure by' becomes 'p' (abbreviation. I am not sure about the 'by' bit.**).
'chief' becomes 'leader' (I've seen this before).
'p'+'leader'='PLEADER'
(Other definitions for pleader that I've seen before include "Advocate" , "Pale red (anag.)" , "Person making case" , "case is made by one" , "one making earnest entreaty" .)