Reticent to eat and drink (6)
I believe the answer is:
shandy
'drink' is the definition.
(shandy is a kind of drink)
'reticent to eat and' is the wordplay.
'reticent' becomes 'shy' (I've seen this before).
'to eat' means one lot of letters goes inside another.
'shy' going around 'and' is 'SHANDY'.
(Other definitions for shandy that I've seen before include "Drink made of beer and lemonade" , "A misture of ale and lemonade" , "Lemonade-beer drink" , "Beer/lemonade mixture" , "Alcohol" .)