Cousins' mothers (5)
I believe the answer is:
aunts
'cousins' mothers' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for aunts that I've seen before include "Female relatives, usually older" , "Parents' sisters" , "Elderly female relations" , "Relatives get a peculiar US tan" , "relatively speaking" .)