Who agreed with one who put down roots? (7)
I believe the answer is:
settler
'who agreed with one' is the definition.
I can't tell whether this definition defines the answer.
'put down roots?' is the wordplay.
'put' becomes 'settle' (settling is a kind of putting).
'down roots?' becomes 'r' (I can't justify this - if you can you should give a lot more credence to this answer).
'settle'+'r'='SETTLER'
'who' is the link.
Can you help me to learn more?
(Other definitions for settler that I've seen before include "Early colonist" , "decisive blow" , "One taking up residence in a new area" , "Person who moves into an uninhabited country" , "who pays his bills" .)