Not quite free to set off in boat (9)
I believe the answer is:
outrigger
'boat' is the definition.
(I've seen this before)
'not quite free to set off' is the wordplay.
'not' becomes 'o' (I've seen this in other clues).
'quite free' becomes 'u' (I am not sure about this - if you are sure you should believe this answer much more).
'to set off' becomes 'trigger' ('trigger' can be a synonym of 'set off').
'o'+'u'+'trigger'='OUTRIGGER'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for outrigger that I've seen before include "projection for various purposes" , "Projecting stabiliser" , "Git, our Reg (anag.); boat" , "Ship's stabilising float" , "Canoe with stabilisers" .)