Arson impeded position-finding (5)

I believe the answer is:

sonar

I'm a little stuck... Click here to teach me more about this clue!

'impeded position-finding' is the definition.
I can't tell whether this definition defines the answer.

'arson' is the wordplay.
'arson' anagrams to 'SONAR'.
Though, I'm not sure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for sonar that I've seen before include "System for locating underwater objects" , "Means of detecting" , "Method of echolocation" , "What a near-blind creature uses" , "echo device" .)

I've seen this clue in The Mirror.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.