The most common and most likely answer to this crossword clue is the 14 letter word BLACK-AND-BLUE
I've seen this crossword clue in Independent
B
L
A
C
K
-
A
N
D
-
B
L
U
E
Buddy explains!
The straight part
We know that "covered in bruises" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case covered in bruises = black-and-blue.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does BLACK-AND-BLUE mean?
BLACK-AND-BLUE adjective- (of a person) Having obvious bruises of the skin, typically from falling or being hit or punched.