turning her into a fairy-tale vegetable, with temperature ready for baking (7)
I believe the answer is:
preheat
'temperature ready for baking' is the definition.
I can't tell whether this defines the answer.
'turning her into a fairy-tale vegetable' is the wordplay.
'turning' says the letters should be written backwards.
'into' is an insertion indicator.
'a fairy tale vegetable' becomes 'peat' (I can't explain this - if you can you should believe this answer much more).
'her' back-to-front is 'reh'.
'reh' going into 'peat' is 'PREHEAT'.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for preheat that I've seen before include "Warm beforehand" , "light oven before food's ready to cook?" .)