Spiritual quality of columns in gallery (9)
I believe the answer is:
godliness
'spiritual quality' is the definition.
'godliness' can be an answer for 'quality' (godliness is a kind of quality). I am not sure about the 'spiritual' bit.
'columns in gallery' is the wordplay.
'columns' becomes 'lines' (I can't justify this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'gallery' becomes 'gods' (I've seen this in other clues).
'lines' placed inside 'gods' is 'GODLINESS'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for godliness that I've seen before include "Piety" , "Respectful behaviour" , "reputedly close to being clean" , "'Cleanliness is akin to . . . . . . . . .'" , "A virtue" .)