Cry of fright (3)
I believe the answer is:
eek
'cry of fright' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for eek that I've seen before include "Expression of mild alarm" , "I'm frightened!" , "Sound of alarm" , "Yikes! Oo-er!" , "Expression of surprise" .)