Device leaders from Capitol Hill introduced to state (7)
I believe the answer is:
machine
'device' is the definition.
(I know that machine is a type of device)
'leaders from capitol hill introduced to state' is the wordplay.
'leaders from' indicates taking the first letters.
'introduced to' is an insertion indicator.
'state' becomes 'maine' (US state).
The first letters of 'capitol hill' is 'ch'.
'ch' put within 'maine' is 'MACHINE'.
(Other definitions for machine that I've seen before include "Device for work" , "Automaton" , "political organisation" , "Well-organised and powerful group" , "Apparatus to perform a specific function" .)