Religious group a church head set out to form (4)

I believe the answer is:

sect

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'religious group' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

(Other definitions for sect that I've seen before include "Religious faction" , "Denomination" , "party" , "Subdivision of a religion" , "Dissenting clique of a religion" .)

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