Prize required for astrophysicist (6)
I believe the answer is:
trophy
'prize' is the definition.
(I know that prize can be written as trophy)
'required for astrophysicist' is the wordplay.
'required for' says the answer is hidden in the clue.
'TROPHY' can be found hidden inside 'astrophysicist'.
(Other definitions for trophy that I've seen before include "Prize of war" , "Award for victory" , "Object awarded as token of victory" , "Cup, say, awarded as a prize for victory or success" , "Kind of wife" .)