Structure employed in perpendicular churches (4)
I believe the answer is:
arch
'structure' is the definition.
(I know that arch is a type of skeletal structure)
'employed in perpendicular churches' is the wordplay.
'employed in' indicates the answer is hidden within the clue.
'ARCH' is hidden in the letters of 'perpendicular churches'.
(Other definitions for arch that I've seen before include "Curved vault" , "Affectedly playful like senior angel" , "Playfully superior" , "Cunning; span" , "Chief - part of foot" .)