Starts to question unusual inventor patenting joke (4)
I believe the answer is:
quip
'joke' is the definition.
(a quip is a joke or witticism)
'starts to question unusual inventor patenting' is the wordplay.
'starts to' indicates taking the first letters.
The first letters of 'question unusual inventor patenting' is 'QUIP'.
(Other definitions for quip that I've seen before include "Witty or sarcastic remark" , "Clever one-liner" , "Witty comment" , "Off-the-cuff joke" , "Quick witty remark" .)