Investigative journey in haste (10)
I believe the answer is:
expedition
This could be a double definition.
'investigative journey' is the first definition.
'expedition' can be an answer for 'journey' (expedition is a kind of journey). I'm unsure of the 'investigative' bit.
'haste' is the second definition.
(expedition can mean doing something speedily)
'in' acts as a link.
Can you help me to learn more?
(Other definitions for expedition that I've seen before include "journey" , "Quest" , "Promptness" , "haste" , "Dispatch" .)