You’ll need it for the roast - and turn the veg on, dear (4,5)
I believe the answer is:
oven glove
'you'll need it for the roast' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.
'turn the veg on dear' is the wordplay.
'turn' is an anagram indicator.
'dear' becomes 'love' (synonyms).
'veg'+'on'='vegon'
'vegon' anagrammed gives 'oveng'.
'oveng'+'love'='OVEN GLOVE'
'and' acts as a link.
Can you help me to learn more?
(Other definitions for oven glove that I've seen before include "Chef has a hand in this" , "obstruction to warmth" , "Protection for cook's hand" .)