German apt to become a star (9)
I believe the answer is:
pentagram
'a star' is the definition.
(I know that pentagram is a type of star)
'german apt to become' is the wordplay.
'to become' indicates anagramming the letters.
'german'+'apt'='germanapt'
'germanapt' with letters rearranged gives 'PENTAGRAM'.
(Other definitions for pentagram that I've seen before include "Five-pointed star" , "Mystical symbol" , "magical symbol" , "Five pointed star" , "Star-shaped figure" .)