Mum's start off like the rest (6)
I believe the answer is:
others
'the rest' is the definition.
(I've seen this before)
'mum's start off' is the wordplay.
'mum's' becomes 'mother's'.
'start off' means to remove the first letter (the start of the word is taken off).
'mothers' with its initial letter taken off is 'OTHERS'.
'like' is the link.
(Other definitions for others that I've seen before include "He rots (anag.)" , "Different ones" , "Different from those already mentioned" , "Certainly not us" , "Not the same one already mentioned" .)