The most common and most likely answer to this crossword clue is the 16 letter word AROUND-THE-CLOCK
I've seen this crossword clue in Financial Times
A
R
O
U
N
D
-
T
H
E
-
C
L
O
C
K
Buddy explains!
The straight part
We know that "all the time" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case all the time = around-the-clock.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 AROUND-THE-CLOCK mean?
AROUND-THE-CLOCK adjective- All day and night; all of the time.