Daughter left covered with unfortunately oily soap (6)

I believe the answer is:

dallas

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'oily soap' is the definition.
'dallas' can be an answer for 'soap' (I've seen this before). I'm unsure of the 'oily' bit.

'daughter left covered with unfortunately' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'left' becomes 'l' (common abbreviation).
'covered with' means one lot of letters goes inside another.
'unfortunately' becomes 'alas' ('alas' is used to express regret).
'l' going inside 'alas' is 'allas'.
'd'+'allas'='DALLAS'

Can you help me to learn more?

(Other definitions for dallas that I've seen before include "The Ewing family saga" , "American city where JFK was killed" , "Texan city and TV series of the 80s" , "Texas city where JFK was assassinated" , "assassination site" .)

I've seen this clue in The Independent.

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