Floorboard sound (5)
I believe the answer is:
'floorboard sound' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for creak that I've seen before include "Audibly reveal weakness under strain" , "Unoiled hinge sound" , "Harsh squeaking noise" , "harsh squeal" , "Squeaking sound" .)