Check on board earlier ship (8)
I believe the answer is:
schooner
'ship' is the definition.
(I've seen this before)
'check on board earlier' is the wordplay.
'check' becomes 'ch' (I've seen this in other clues).
'on board' is an insertion indicator.
'earlier' becomes 'sooner' ('sooner' can be a synonym of 'earlier').
'ch' placed inside 'sooner' is 'SCHOONER'.
(Other definitions for schooner that I've seen before include "Old sailing vessel and large glass" , "boat" , "Sailing vessel used in former times" , "Measure for sherry or kind of sailing ship" , "No chores on this sailing ship" .)