Barristers reach good deal (7)
I believe the answer is:
bargain
'good deal' is the definition.
(I've seen this before)
'barristers reach' is the wordplay.
'barristers' becomes 'bar' (the bar can mean the legal profession).
'reach' becomes 'gain' (synonyms).
'bar'+'gain'='BARGAIN'
(Other definitions for bargain that I've seen before include "An agreement, or thing got cheaply" , "Deal; item at low price" , "Deal; cheap buy" , "Special offer" , "Good-value purchase" .)