Oxford University set off in boat (9)
I believe the answer is:
outrigger
'boat' is the definition.
(I've seen this before)
'oxford university set off' is the wordplay.
'oxford university' becomes 'OU'.
'set off' becomes 'trigger' (synonyms).
'ou'+'trigger'='OUTRIGGER'
'in' acts as a link.
(Other definitions for outrigger that I've seen before include "Ship's stabilising float" , "Type of boat with external supports" , "Git, our Reg (anag.); boat" , "projection for various purposes" , "Craft" .)