Astronomer Fred takes year inside crater (5)
I believe the answer is:
hoyle
'astronomer fred' is the definition.
(English astronomer Fred Hoyle)
'year inside crater' is the wordplay.
'year' becomes 'y'.
'inside' indicates putting letters inside.
'crater' becomes 'hole'.
'y' going within 'hole' is 'HOYLE'.
'takes' is the link.
(Other definitions for hoyle that I've seen before include "cosmologist" , "English astrophysicist, who coined the term "big bang", d. 2001" , "English writer on card games" , "Sir Fred --, astronomer" , "Edmond --, early writer on card games" .)