Strain shown by architect attending church (6)
I believe the answer is:
wrench
'strain' is the definition.
(thesaurus)
'architect attending church' is the wordplay.
'architect' becomes 'Wren' (Christopher Wren, 17th-century architect).
'attending' means one lot of letters go next to another.
'church' becomes 'ch' (common abbreviation).
'wren'+'ch'='WRENCH'
'shown by' is the link.
(Other definitions for wrench that I've seen before include "Violent twist; tool" , "Jerky pulling movement" , "Twist violently around" , "Yank" , "Violent twist - (adjustable) spanner" .)