Large building greatly revered, though not outstanding (4)
I believe the answer is:
hall
'large building greatly' is the definition.
I can't judge whether this definition defines the answer.
'revered though not outstanding' is the wordplay.
'revered' becomes 'hallowed' (I've seen this before).
'though not' suggests deleting specific letters.
'outstanding' becomes 'owed' ('owed' can be a synonym of 'outstanding').
'hallowed' with 'owed' taken away is 'HALL'.
Can you help me to learn more?
(Other definitions for hall that I've seen before include "Building used for public assembly" , "College dinner; passage" , "Large country house" , "Large house (linked to Dotheboys, Wildfell and Toad)" , "College dining room" .)