Bed starts to creak — replace its base (4)
I believe the answer is:
Here is my best explanation:
'bed' is the definition.
'starts to creak replace its base' is the subsidiary indication.
'starts to' says to take the initial letters.
The initial letters of 'creak replace its base' is 'crib'.
(Other definitions for crib that I've seen before include "Cheat - Christmas scene", "Baby's bed", "Card game for two", "Cot; translation cheat", "Poor translation", "Student's aid; bed", "Copy; bed", "Manger; illegally copy", "Bed; copy" and "Plagiarise - cot".)