The most common and most likely answer to this crossword clue is the 8 letter word DURATION
I've seen this crossword clue in The Times
D
U
R
A
T
I
O
N
More clues leading to the result DURATION
- Time taken spreading it around
- Fluid around it the whole time
- Time taken to move around it
- Stretch half of duck portion
- Length of time around it varied
- Fraction split tax period
- ‘Time’ ultimately granted uniform allowance
- Dull colour’s kept in proportion the last time?
- I do a turn, being funny for a time
- It’s boring, not half, helping for a time
Buddy explains!

The straight part
We know that "the whole time" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the whole time = duration.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 DURATION mean?
DURATION noun- An amount of time or a particular time interval.
- (in the singular, not followed by "of") The time taken for the current situation to end, especially the current war
- A measure of the sensitivity of the price of a financial asset to changes in interest rates, computed for a simple bond as a weighted average of the maturities of the interest and principal payments associated with it.