Get in a mess having a meal (6)
I believe the answer is:
eating
'having a meal' is the definition.
(I've seen this in another clue)
'get in a mess' is the wordplay.
'mess' indicates anagramming the letters.
'get'+'in'+'a'='getina'
'getina' anagrammed gives 'EATING'.
(Other definitions for eating that I've seen before include "Out to dinner?" , "Ingestion" , "Having supper?" , "Consuming food" , "Putting away" .)