Part — or place? — of union (6)
I believe the answer is:
chapel
'place? of union' is the definition.
'chapel' can be an answer for 'place?' (I have seen 'Place of worship ' mean 'chapel' so perhaps 'place' could also mean 'chapel'). I am not sure about the 'of union' bit.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for chapel that I've seen before include "house of prayer" , "Branch of a newspaper trade union" , "Nonconformist church" , "Local printers" , "Part of or alternative to church" .)