Great deal of money in parcel (6)
I believe the answer is:
packet
This might be a double definition.
'great deal' is the first definition.
(thesaurus)
'money in parcel' is the second definition.
'packet' can be an answer for 'parcel' (synonyms). I am unsure of the 'money in' bit.
'of' is the link.
Can you help me to learn more?
(Other definitions for packet that I've seen before include "Paper or cardboard container" , "A lot of money that may be lost" , "Container; much money" , "Boat carrying mail" , "Small parcel" .)