The most common and most likely answer to this crossword clue is the 6 letter word TWELVE
I've seen this crossword clue in The Sunday Telegraph
T
W
E
L
V
E
More clues leading to the result TWELVE
- Roman cardinals wearing pretty number
- The Guardian joining line in the box with electronic figure
- Noon temperature fifty-five, in short
- Number of centuries needed for MCC? 4, perhaps
- Highest number on clock in taxi indicated?
- Number of days in present period
- A time for high-handedness
- Time when the hands come together
- Live on and off in quaint housing that’s left here?
- Time you and I have to grab a little bit of lunch?
Buddy explains!

The straight part
We know that "Number of days in present period" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case number of days in present period = twelve.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 TWELVE mean?
TWELVE noun- A group of twelve items.
- A twelve-bore gun.
- A jury (normally composed of twelve persons).
- Police; law enforcement, especially a narcotics officer
- The cardinal number occurring after eleven and before thirteen, represented in Arabic numerals as 12 and in Roman numerals as XII.
- Law enforcement; the police