Cardinal still in filthy place (7)
I believe the answer is:
seventy
'cardinal' is the definition.
('seventy' can be similar in meaning to 'cardinal')
'still in filthy place' is the wordplay.
'still' becomes 'even' ('even' can be a synonym of 'still').
'in' is an insertion indicator.
'filthy place' becomes 'sty' (I've seen this before).
'even' put within 'sty' is 'SEVENTY'.
(Other definitions for seventy that I've seen before include "LXX" , "Threescore and ten" , "A number" , "Three score years and ten" .)