The most common and most likely answer to this crossword clue is the 11 letter word THERMOSTATS
I've seen this crossword clue in The Guardian
T
H
E
R
M
O
S
T
A
T
S
Buddy explains!

The straight part
We know that "regulators" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case regulators = thermostats.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 THERMOSTATS mean?
THERMOSTATS noun- A device that automatically responds to changes in temperature by activating a heating or cooling system to maintain the temperature at a desired setting.