Construction of largely new altar in cathedral church of Rome (7)
I believe the answer is:
lateran
'cathedral church of rome' is the definition.
I can't tell whether this definition defines the answer.
'construction of largely new altar' is the wordplay.
'construction of' indicates an anagram (I've seen 'construction' mean this (answer constructed from certain letters)).
'largely' means to remove the last letter.
'new' with its final letter removed is 'ne'.
'ne'+'altar'='nealtar'
'nealtar' with letters rearranged gives 'LATERAN'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for lateran that I've seen before include "Of a particular Roman district; an alert, anag." , "St John --, church in Rome" , "Church council" , "Palace" , "Old council" .)