Crossword Genius

Cathedral feature mounted by bereft woman (name to be inserted)? (4,6)

Ross

I believe the answer is:

rose window

I'm a little stuck... Click here to teach me more about this clue!

'cathedral feature' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.

'mounted by bereft woman name to be inserted?' is the wordplay.
'mounted' becomes 'rose' (I've seen this before).
'by bereft woman' becomes 'widow' (I can't justify this - if you can you should believe this answer much more).
'name' becomes 'n' (common abbreviation e.g. on forms).
'to be inserted?' indicates putting letters inside.
'widow' going around 'n' is 'window'.
'rose'+'window'='ROSE-WINDOW'

Can you help me to learn more?

(Other definitions for rose window that I've seen before include "feature in church" , "Light" .)

I've seen this clue in The Guardian.
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