Wish, Sir, to get into unfinished deed? (6)
I believe the answer is:
desire
'wish' is the definition.
(I know that wish is a more specific form of the action desire)
'sir to get into unfinished deed?' is the wordplay.
'to get into' is an insertion indicator.
'unfinished' means to remove the last letter.
'deed' with its last letter taken away is 'dee'.
'sir' put within 'dee' is 'DESIRE'.
(Other definitions for desire that I've seen before include "Reside (anag.)" , "Strong need" , "Want strongly" , "request" , "Lust" .)