A tout planned to go round Britain -- in this vessel? (7)
I believe the answer is:
tugboat
'this vessel?' is the definition.
(tugboat is a kind of vessel)
'a tout planned to go round britain' is the wordplay.
'planned' is an anagram indicator.
'to go round' indicates putting letters inside.
'britain' becomes 'gb'.
'a'+'tout'='atout'
'atout' with letters rearranged gives 'tuoat'.
'tuoat' going around 'gb' is 'TUGBOAT'.
'in' acts as a link.
(Other definitions for tugboat that I've seen before include "Ship pulling a larger one" , "Small vessel pulling a big one" , "Vessel drawing" , "Powerful vessel used to pull larger ones" , "Vessel towing larger vessels" .)