A line company promoted in proper state (8)
I believe the answer is:
proclaim
'state' is the definition.
(thesaurus)
'a line company promoted in proper' is the wordplay.
'line' becomes 'l' (used when specifying particular lines from a poem).
'company' becomes 'co' (abbreviation).
'promoted' says the letters should be written backwards (going up, in a down clue).
'in' means one lot of letters goes inside another.
'proper' becomes 'prim' (prim and proper).
'a'+'l'+'co'='alco'
'alco' written backwards gives 'ocla'.
'ocla' placed inside 'prim' is 'PROCLAIM'.
(Other definitions for proclaim that I've seen before include "Declare formally" , "Speak out" , "Broadcast" , "Herald" , "Announce officially or declare publicly" .)