Ruth holding hollow glass pen (6)
I believe the answer is:
pigsty
'pen' is the definition.
(pigsty is a kind of pen)
'ruth holding hollow glass' is the wordplay.
'ruth' becomes 'pity' ('pity' can be a synonym of 'ruth').
'holding' indicates putting letters inside.
'hollow' means to remove the middle letters.
'glass' with its centre removed is 'gs'.
'pity' going around 'gs' is 'PIGSTY'.
(Other definitions for pigsty that I've seen before include "Dirty domicile" , "Dirty place; animal pen" , "Porker pen" , "Porcine pen" , "messy situation" .)