Dim carnivore eating head of lettuce (5)
I believe the answer is:
blear
'dim' is the definition.
(I've seen this in another clue)
'carnivore eating head of lettuce' is the wordplay.
'carnivore' becomes 'bear' (bear is a kind of carnivore).
'eating' means one lot of letters goes inside another.
'head of' says to take the initial letters.
The initial letter of 'lettuce' is 'l'.
'bear' enclosing 'l' is 'BLEAR'.
(Other definitions for blear that I've seen before include "Baler (anag.)" , "Make (the eyes) dim" , "Blur" , "Watery, blurred" , "Indistinct" .)