Ring the doctor; it finishes my curiosity (6)
I believe the answer is:
oddity
'curiosity' is the definition.
(I know that curiosity can be written as oddity)
'ring the doctor it finishes my' is the wordplay.
'ring' becomes 'O' (letter resembling a ring).
'the doctor' becomes 'dd' (Doctor of Divinity).
'finishes' says to take the final letters (I've seen 'finish of' mean this).
The final letter of 'my' is 'y'.
'o'+'dd'+'it'+'y'='ODDITY'
(Other definitions for oddity that I've seen before include "Curious item" , "Family relative" , "Strange person/thing" , "Something peculiar, person or event" , "Quality of strangeness" .)