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 judge whether this definition defines the answer.
'turning her into a fairy-tale vegetable' is the wordplay.
'turning' is a reversal indicator.
'into' indicates putting letters inside.
'a fairy tale vegetable' becomes 'peat' (I am not sure about this - if you are sure you should believe this answer much more).
'her' reversed gives 'reh'.
'reh' inserted inside 'peat' is 'PREHEAT'.
'with' is the 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?" .)