Hens and leverets fighting still (12)
I believe the answer is:
nevertheless
'still' is the definition.
(I know that still can be written as nevertheless)
'hens and leverets fighting' is the wordplay.
'and' means one lot of letters go next to another.
'fighting' indicates an anagram (I've seen this in other clues).
'hens' put after 'leverets' is 'leveretshens'.
'leveretshens' anagrammed gives 'NEVERTHELESS'.
(Other definitions for nevertheless that I've seen before include "Notwithstanding" , "In spite of everything" , "Still" , "anyhow" , "at any rate" .)