'American Way' missing Republican, lacking a will (9)
I believe the answer is:
intestate
'lacking a will' is the definition.
(I've seen this before)
'american way missing republican' is the wordplay.
'american way' becomes 'interstate' (I've seen this before).
'missing' is a deletion indicator.
'republican' becomes 'r' (abbreviation).
'interstate' with 'r' taken out is 'INTESTATE'.
(Other definitions for intestate that I've seen before include "Dying thus, one has left no will" , "Lacking a will" , "Undecided about who should inherit" , "One without will" , "Passing on without leaving a will" .)