Composer taking up bird without tail (4)
I believe the answer is:
berg
'composer' is the definition.
(Alban Berg, 1885 - 1935)
I cannot understand how the remainder of the clue works.
(Other definitions for berg that I've seen before include "South African hill - Austrian composer" , "Austrian composer of 12-tone music, d. 1935" , "famously cut short a transatlantic journey" , "Mountain (in German, South African)" , "African mount" .)