Missile shelter Rhode Island Democrat enters (7)
I believe the answer is:
trident
'missile' is the definition.
(I've seen this before)
'shelter rhode island democrat enters' is the wordplay.
'shelter' becomes 'tent' (tent is a kind of shelter).
'rhode island' becomes 'ri' (US postal abbreviation).
'democrat' becomes 'd'.
'enters' indicates putting letters inside.
'ri'+'d'='rid'
'tent' going around 'rid' is 'TRIDENT'.
(Other definitions for trident that I've seen before include "Neptune's or Britannia's spear" , "Three-pointed spear" , "spear carried at sea" , "Neptune's fork" , "Nuclear missile" .)