The most common and most likely answer to this crossword clue is the 7 letter word BOOTEES
I've seen this crossword clue in The Times
B
O
O
T
E
E
S
Buddy explains!

The straight part
We know that "Knitted footwear" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case knitted footwear = bootees.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 BOOTEES mean?
BOOTEES noun- A soft, woolen shoe, usually knitted, for a baby or small pet.
- A thick sock worn under a wetsuit.
- An overshoe or sock worn to cover dirty shoes or feet.