Seamen like part of a church, we're told? (4)
I believe the answer is:
navy
'seamen' is the definition.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for navy that I've seen before include "Armed force" , "Senior service" , "Marine force" , "Ships-of-war" , "Blue - ships and seamen" .)