The most common and most likely answer to this crossword clue is the 8 letter word RADIATOR
R
A
D
I
A
T
O
R
More clues leading to the result RADIATOR
- Heater that's cooler for car
- Engine cooler but house warmer
- Heater or cooler?
- In retrospect, ‘rubbish’ opera right? Its content is wet!
- Heater that’s cooler for car
- It may be cooler in a saloon, but it’s warmer at home
- What could make an estate cool, perhaps
- Cool mountain lodges brought up first class heater
- Wireless picks up origins of alien transmission — reading it could heat things up
Buddy explains!

The straight part
We know that "heater" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case heater = radiator.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 RADIATOR mean?
RADIATOR noun- Anything which radiates or emits rays.
- A device that lowers engine coolant temperature by conducting heat to the air, through metal fins.
- (of buildings) A finned metal fixture that carries hot water or steam in order to heat a room.
- A type of antenna.