Mushy Murphy beaten with one holding ketamine inside? (7)

I believe the answer is:

mawkish

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'mushy' is the definition.
(I know that mushy can be written as mawkish)

I don't understand how the remainder of the clue works.

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(Other definitions for mawkish that I've seen before include "Cloying" , "Falsely sentimental" , "Sentimental in maudlin way" , "Effusively or insincerely emotional" , "Soppy" .)

I've seen this clue in The Independent.

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