Crossword Genius

Aren't ropes aboard ship in irreproachable condition? (11)

Ross

I believe the answer is:

saintliness

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

'irreproachable condition?' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.

'aren't ropes aboard ship' is the wordplay.
'aren't' becomes 'ain't' (non-standard version of 'isn't' or 'aren't').
'ropes' becomes 'lines' (I can't justify this - if you can you should give a lot more credence to this answer).
'aboard' means one lot of letters goes inside another.
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'aint'+'lines'='aintlines'
'aintlines' going into 'ss' is 'SAINTLINESS'.

'in' is the link.

Can you help me to learn more?

(Other definitions for saintliness that I've seen before include "Least in sins (anag)" , "being very good" .)

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