The most common and most likely answer to this crossword clue is the 6 plus 9 letter word CARBON FOOTPRINT
I've seen this crossword clue in The Daily Telegraph
C
A
R
B
O
N
F
O
O
T
P
R
I
N
T
More clues leading to the result CARBON FOOTPRINT
- Copy infantry photo: how much one adds to the atmosphere!
- How to track down a supplier of fossil fuels?
- Green measurement of coal essentially on track
- Environmental measure taken from miners’ track, maybe?
- Elementary impression of energy efficiency
- Caught baron prepared to pay and publish effect on planet
- Walking into motor oil company, runs into reduced cost of fossil fuel
- One’s fuel consumption is about right? Sadly no on trip to Belgium and France
- Copy and measure picture’s emissions
- Additional copy includes a measure of greenhouse emissions
Buddy explains!
The straight part
We know that "effect on planet" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case effect on planet = carbon footprint.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.