Vessel manoeuvre: starting to go about (7)
I believe the answer is:
tugboat
'vessel' is the definition.
(tugboat is a kind of vessel)
'manoeuvre starting to go about' is the wordplay.
'manoeuvre' indicates anagramming the letters.
'starting' suggests taking the first letters.
The first letters of 'to go' is 'tg'.
'tg'+'about'='tgabout'
'tgabout' with letters rearranged gives 'TUGBOAT'.
(Other definitions for tugboat that I've seen before include "Ship pulling a larger one" , "Harbour craft" , "Vessel towing larger vessels" , "water tower" , "Vessel drawing" .)