Ship companion boarding earlier (8)
I believe the answer is:
schooner
'ship' is the definition.
(I've seen this before)
'companion boarding earlier' is the wordplay.
'companion' becomes 'ch' (Companion of Honour).
'boarding' means one lot of letters goes inside another.
'earlier' becomes 'sooner' (synonyms).
'ch' going within 'sooner' is 'SCHOONER'.
(Other definitions for schooner that I've seen before include "Two-masted sailing ship" , "Sailing vessel - drinking vessel" , "A measure or glass for sherry" , "9 [CONTAINER" , "Type of glass" .)