Trouble opening up in place of worship (6)
I believe the answer is:
pagoda
'place of worship' is the definition.
(pagoda is a kind of place of worship)
'trouble opening up' is the wordplay.
'trouble' becomes 'ado' (I've seen this before).
'opening' becomes 'gap' (gap is a kind of opening**).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'ado'+'gap'='adogap'
'adogap' reversed gives 'PAGODA'.
'in' acts as a link.
(Other definitions for pagoda that I've seen before include "Oriental temple, often a tower" , "Hindu or Buddhist temple" , "Many-tiered building" , "place of worship" , "religious structure" .)