Salvage only half complete? I expected this to be over (7)

I believe the answer is:

residue

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'this to be over' is the definition.
The definition suggests a singular noun which matches the answer.

'salvage only half complete? i expected' is the wordplay.
'salvage' becomes 'rescue' (I've seen this before).
'only half complete?' indicates taking half.
'expected' becomes 'due' (similar in meaning).
'rescue' with half the letters taken is 'res'.
'res'+'i'+'due'='RESIDUE'

Can you help me to learn more?

(Other definitions for residue that I've seen before include "What's left" , "Deposit" , "Stuff left over" , "Net worth of estate" , "Small amount remaining" .)

I've seen this clue in The Times.

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