The most common and most likely answer to this crossword clue is the 9 letter word INDICATOR
I've seen this crossword clue in The Sunday Telegraph
I
N
D
I
C
A
T
O
R
More clues leading to the result INDICATOR
- Sign one might be on the blink?
- Flasher in coat I’d sadly seen by river
- In flipping list, police showing flasher in road
- It shows popular autocrat taking first time off
- Popular autocrat has no time initially for signal
- Sign in designer pet boarding
- Guide for much-loved autocrat short of time
- Idiot messed around with car, installing new gauge
- Mark in register police group reviewed
- This shows acid, or tin compounds
Buddy explains!

The straight part
We know that "This shows" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case this shows = indicator.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 INDICATOR mean?
INDICATOR noun- A pointer or index that indicates something.
- A meter or gauge.
- The needle or dial on such a meter.
- Any of many substances, such as litmus, used to indicate the concentration of a substance, or the degree of a reaction.
- A plant or animal whose presence is indicative of some specific environment.
- A measure, such as unemployment rate, which can be used to predict economic trends.
- A turn signal; each of the flashing lights on each side of a vehicle which indicate a turn is being made to left or right, or a lane change etc.
- A bird, the honeyguide.