The most common and most likely answer to this crossword clue is the 7 letter word BLANKET
I've seen this crossword clue in The Daily Telegraph
B
L
A
N
K
E
T
More clues leading to the result BLANKET
- Cover is void except on vacation
- Coverage of space alien
- General risk to keep thin
- All-inclusive cover for retirement
- Wrap boy’s broken ankle with some kind of shirt
- Risk securing limp cover
- General to risk eating lean
- Pretend not to notice Spielberg film coverage
- Empty headed alien’s means of keeping warm
- Broad coverage
Buddy explains!

The straight part
We know that "cover" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cover = blanket.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 BLANKET mean?
BLANKET noun- A heavy, loosely woven fabric, usually large and woollen, used for warmth while sleeping or resting.
- A layer of anything.
- A thick rubber mat used in the offset printing process to transfer ink from the plate to the paper being printed.
- A streak or layer of blubber in whales.
- To cover with, or as if with, a blanket.
- To traverse or complete thoroughly.
- To toss in a blanket by way of punishment.
- To take the wind out of the sails of (another vessel) by sailing to windward of it.
- To nullify the impact of someone or something.
- General; covering or encompassing everything.