Sailing ship: grand one at sea impressing everyone (7)
I believe the answer is:
galleon
'sailing ship' is the definition.
(I know that galleon is a type of sailing ship)
'grand one at sea impressing everyone' is the wordplay.
'grand' becomes 'g' (G is short for grand as in a thousand).
'at sea' is an anagram indicator.
'impressing' is an insertion indicator (impress historically meant to conscript).
'everyone' becomes 'all' (all people).
'one' is an anagram of 'eon'.
'eon' placed around 'all' is 'alleon'.
'g'+'alleon'='GALLEON'
(Other definitions for galleon that I've seen before include "Trader" , "Spanish treasure ship" , "Large old square-rigged sailing ship" , "Historical warship with three or more masts" , "Old Spanish war-ship" .)