Church Street crossed by underground worker (7)
I believe the answer is:
minster
'church' is the definition.
(I know that minster is a type of cathedral)
'street crossed by underground worker' is the wordplay.
'street' becomes 'st' (abbreviation).
'crossed by' means one lot of letters goes inside another (inserted letters are crossed or covered by others).
'underground worker' becomes 'miner' (someone working underground in a mine).
'st' inserted within 'miner' is 'MINSTER'.
(Other definitions for minster that I've seen before include "Abbey or priory church" , "Clergyman" , "Large church (eg, York)" , "Large church (or cathedral at York)" , "Large important church" .)