Hard-up daughter stirs gluey porridge (4,6)
I believe the answer is:
ugly sister
'hard-up daughter' is the definition.
(one of Baron Hard-up's daughters in Cinderella)
'stirs gluey porridge' is the wordplay.
'porridge' indicates anagramming the letters (a porridge or mixture of the letters).
'stirs'+'gluey'='stirsgluey'
'stirsgluey' with letters rearranged gives 'UGLY SISTER'.
(Other definitions for ugly sister that I've seen before include "Cinderella tormentor" , "One living with Cinderella" .)