No, no! Come back around lunchtime for something to eat (5)
I believe the answer is:
onion
'something to eat' is the definition.
(onion is a kind of food)
'no no come back around lunchtime' is the wordplay.
'come back' says the letters should be written backwards.
'around' indicates putting letters inside.
'lunchtime' becomes 'i' (1pm could be I on a clock with Roman numerals).
'no'+'no'='nono'
'nono' reversed gives 'onon'.
'onon' going around 'i' is 'ONION'.
'for' acts as a link.
(Other definitions for onion that I've seen before include "Tear-jerking bulb" , "Bulb used in cooking" , "Eye-watering vegetable" , "Tear-inducing edible bulb" , "Hot dog topping" .)