Plead a case for right Austrian composer (4)
I believe the answer is:
berg
'austrian composer' is the definition.
(I've seen this before)
'plead a case for right' is the wordplay.
'plead' becomes 'beg' (begging is a kind of pleading**).
'a case for' indicates putting letters inside.
'right' becomes 'r' (common abbreviation).
'beg' going around 'r' is 'BERG'.
(Other definitions for berg that I've seen before include "Shipping hazard; composer" , "Possible shipping hazard" , "Viennese composer" , "Large mass of floating ice" , "South African mountain - Austrian composer" .)