The most common and most likely answer to this crossword clue is the 6 letter word DECADE
I've seen this crossword clue in The Times
D
E
C
A
D
E
More clues leading to the result DECADE
- Declining to scrap scripture period
- Rat in river for some years
- Rogue found in British river in sixties perhaps
- Years of debauchery ignoring religious books
- Went off, you might say, for a number of years
- Dog’s in river for a period
- Period that’s rotten in terms of radio, according to some
- Period of 31 days briefly needing help reportedly
- Rat appearing in river for a number of years
- Ten years of French in place of Arabic in place of amusement
Buddy explains!

The straight part
We know that "period" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case period = decade.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 DECADE mean?
DECADE noun- A group, set, or series of ten , particularly:
- A set of resistors, capacitors, etc. connected so as to provide even increments between one and ten times a base electrical resistance.
- The interval between any two quantities having a ratio of 10 to 1.