Large ship, poor relation boarded by king (3,6)

I believe the answer is:

oil tanker

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

'large ship' is the definition.
'oil tanker' can be an answer for 'ship' (I've seen this before). I am unsure of the 'large' bit.

'poor relation boarded by king' is the wordplay.
'poor' is an anagram indicator.
'boarded by' indicates putting letters inside (I've seen this in other clues).
'king' becomes 'K' (abbreviation for king in chess).
'relation' is an anagram of 'oiltaner'.
'oiltaner' enclosing 'k' is 'OIL-TANKER'.

Can you help me to learn more?

(Other definitions for oil tanker that I've seen before include "Ship carrying "black gold"" , "On which crude" , "Ship carrying fuel" , "boat" , "[See] ocean-going vessel" .)

I've seen this clue in The Times.

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