Protestant clumsily dropping books in part of church (8)
I believe the answer is:
transept
'part of church' is the definition.
('transept' is part of 'church')
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for transept that I've seen before include "Side part of a church" , "Something dividing church in two" , "Crossing part of a church" , "Part of church off aisle" , "Arm of church body" .)