Course followed by Queen's ship (5)
I believe the answer is:
liner
'ship' is the definition.
(liner is a kind of ship)
'course followed by queen's' is the wordplay.
'course' becomes 'line' ('line' can be a synonym of 'course').
'followed by' means one lot of letters go next to another.
'queen' becomes 'r' (r is abbreviation regina. e.g. in ER ).
'line'+'r'='LINER'
(Other definitions for liner that I've seen before include "Pleasure cruiser" , "Large passenger or cargo ship travelling on regular route" , "bin-bag?" , "Large passenger-ship" , "Craft" .)