Is obliged to finish on a positive note, in a hurry! (5)

I believe the answer is:

haste

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

'in a hurry' is the definition.
(I've seen this before)

'is obliged to finish on a positive note' is the wordplay.
'is obliged' becomes 'has'.
'to finish' suggests halving the letters.
'on' becomes 'at' (I've seen this in other clues).
'a positive note' becomes 'e' (musical note. I am not sure about the 'positive' bit.).
'at' with half the letters taken is 't'.
'has'+'t'+'e'='HASTE'

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(Other definitions for haste that I've seen before include "Overly eager speed" , "Speediness or rush" , "''Marry in . . . . ., repent at leisure''" , "Hurry, urgency" , "Leader abandons modest" .)

I've seen this clue in the Evening Standard.

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