Eat in my mess whenever you like! (7)
I believe the answer is:
anytime
'whenever you like' is the definition.
(I've seen this before)
'eat in my mess' is the wordplay.
'mess' indicates anagramming the letters.
'eat'+'in'+'my'='eatinmy'
'eatinmy' anagrammed gives 'ANYTIME'.
(Other definitions for anytime that I've seen before include "Whenever, as it doesn't matter" , "Whenever you like" , "A tiny me (anag.)" , "At no particular moment" , "date not fixed" .)