Ship's policy read at the start (5)
I believe the answer is:
liner
'ship's' is the definition.
(as in an ocean liner)
'policy read at the start' is the wordplay.
'policy' becomes 'line' (the party line is a party's policy on something).
'at the start' indicates taking the first letters.
The first letter of 'read' is 'r'.
'line'+'r'='LINER'
(Other definitions for liner that I've seen before include "cover for interior" , "Cruise ship" , "Large ship or removable layer of material" , "bin-bag?" , "LP's inner sleeve" .)