Call of alarm from jittery hikers (6)
I believe the answer is:
shriek
'call of alarm' is the definition.
'shriek' can be an answer for 'call' (shriek is a kind of call). I am unsure of the 'of alarm' bit.
'jittery hikers' is the wordplay.
'jittery' is an anagram indicator.
'hikers' with letters rearranged gives 'SHRIEK'.
'from' acts as a link.
Can you help me to learn more?
(Other definitions for shriek that I've seen before include "Howl" , "A high-pitched scream" , "Shrill cry of a shrike" , "Scream or squeal" , "Sharp piercing cry" .)