Vessel seen earlier outside church (8)
I believe the answer is:
'vessel' is the definition.
(schooner is a kind of vessel)
'earlier outside church' is the wordplay.
'earlier' becomes 'sooner' (synonyms).
'outside' indicates putting letters inside.
'church' becomes 'ch' (common abbreviation).
'sooner' going around 'ch' is 'SCHOONER'.
'seen' acts as a link.
(Other definitions for schooner that I've seen before include "Measure for sherry or kind of sailing ship" , "Old sailing vessel and large glass" , "In the main it is" , "Two-masted sailing ship" , "No chores on this sailing ship" .)