Strength shown by leaders in Scottish church inspired by cross (6)
I believe the answer is:
muscle
'strength' is the definition.
(muscle is a kind of strength)
'leaders in scottish church inspired by cross' is the wordplay.
'leaders in' says to take the initial letters.
'inspired by' means one lot of letters goes inside another (some letters breathed in or 'inspired' by others).
'cross' becomes 'mule' (I've seen this before).
The initial letters of 'scottish church' is 'sc'.
'sc' inserted within 'mule' is 'MUSCLE'.
'shown by' is the link.
(Other definitions for muscle that I've seen before include "elevator, for instance" , "meat" , "Fibrous tissue in the body" , "Body tissue - strength" , "Body tissue that expands and contracts" .)