He penned hits, some unfinished sadly? (7,8)

I believe the answer is:

stephen sondheim

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'he penned hits some unfinished sadly?' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.

'he penned hits some unfinished sadly?' is the wordplay.
'unfinished' means to remove the last letter.
'sadly?' indicates anagramming the letters (I've seen 'sadly' mean this).
'he'+'penned'+'hits'+'some'='hepennedhitssome'
'hepennedhitssome' with its final letter removed is 'hepennedhitssom'.
'hepennedhitssom' with letters rearranged gives 'STEPHEN SONDHEIM'.

Can you help me to learn more?

(Another definition for stephen sondheim that I've seen is " composer".)

I've seen this clue in The Everyman puzzle in The Observer.

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