The most common and most likely answer to this crossword clue is the 7 letter word CLARION
I've seen this crossword clue in The Daily Telegraph
C
L
A
R
I
O
N
More clues leading to the result CLARION
- Old brass instrument Caroline mostly played
- Tribe besieging city produces trumpet
- Such inspiring call from family about Brazilian port
- Trumpet band traverses South American city
- Port in Scottish house inspiring caller
- Clear sort of call from family touring port
- Tribal lot round port producing kind of trumpet
- Port in Scottish house for caller
- Like call for action, seeing liar involved in scam
- Caller, perhaps, from family bordering Spanish river
Buddy explains!

The straight part
We know that "Clear sort of call" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case clear sort of call = clarion.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 CLARION mean?
CLARION noun- A medieval brass instrument, related to the trumpet, or its sound.
- A different type of musical instrument resembling an organ.
- To sound a clarion (trumpet-like instrument).
- To make a similar sound to the instrument.