Ship’s front that takes a long time to pass (7)
I believe the answer is:
galleon
'ship's' is the definition.
(type of ship)
'front that takes a long time to pass' is the wordplay.
'front' becomes 'gall' (both can mean audacity or insolence).
'that takes a long time to pass' becomes 'eon' (an eon is a very long time).
'gall'+'eon'='GALLEON'
(Other definitions for galleon that I've seen before include "Large old square-rigged sailing ship" , "Large Spanish sailing ship of yore" , "Spanish treasure ship" , "Large old sailing vessel" , "One might sink" .)