Threaten to get money (6)
I believe the answer is:
extort
'get money' is the definition.
'extort' can be an answer for 'get' (thesaurus). I am unsure of the 'money' bit.
'threaten to' is the wordplay.
I cannot really see how this works, but
'to' is within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for extort that I've seen before include "Wring (money) out (by violence, etc)" , "Obtain wrongfully" , "Compel to pay" , "Blackmail" , "Force from, tax or confession" .)