Cardinal seen in a Catholic hospital (4)
I believe the answer is:
arch
'cardinal' is the definition.
(thesaurus)
'a catholic hospital' is the wordplay.
'catholic' becomes 'rc' (I've seen this in other clues).
'hospital' becomes 'h'.
'a'+'rc'+'h'='ARCH'
'seen in' is the link.
(Other definitions for arch that I've seen before include "Curve that spans an opening" , "Consummate" , "Affectedly playful like senior angel" , "Curved masonry construction" , "a piece about a foot?" .)