A squeaky-sounding "Hurry!" (3)
I believe the answer is:
hie
'hurry' is the definition.
(historical word meaning go quickly or hasten)
'a squeaky-sounding' is the wordplay.
'a squeaky' becomes 'hi' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'sounding' becomes 'e' (I've seen this in other clues).
'hi'+'e'='HIE'
Can you help me to learn more?
(Other definitions for hie that I've seen before include "make haste" , "Hasten" , "Hurry" , "Go quickly (archaic)" , "Make one's way quickly" .)