European tucks into dull food (4)
I believe the answer is:
meat
'food' is the definition.
(meat is a kind of food)
'european tucks into dull' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'tucks into' indicates putting letters inside.
'dull' becomes 'mat' ('mat' can be similar in meaning to 'dull').
'e' inserted into 'mat' is 'MEAT'.
(Other definitions for meat that I've seen before include "Ham, pork, chicken etc" , "Animal flesh as food" , "Beef, chicken, pork etc" , "grub, say" , "Edible flesh" .)