Decline right away, leading to death (7)
I believe the answer is:
decease
'death' is the definition.
(I know that death can be written as decease)
'decline right away' is the wordplay.
'decline' becomes 'decrease' (I've seen this before).
'right' becomes 'r' (common abbreviation).
'away' suggests deleting specific letters.
'decrease' with 'r' taken out is 'DECEASE'.
'leading to' acts as a link.
(Other definitions for decease that I've seen before include "Death, die" , "end of life" .)