15 across
Root
of
change
I
proposed
initially
(6)
Root of change I proposed initially (6)
hints
0
checks
0
hints
The definition is at the beginning of the clue.
How the clue works
Right, so Root is the definition — some kind of root vegetable. For the wordplay, take TURN (meaning change), then bolt on I, then finish with P, which is just the initial letter of "proposed" — TURN plus I plus P gives you the veg in question.