Banker makes rate become more positive (9)
I believe the answer is:
treasurer
'banker' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'rate become more positive' is the wordplay.
'become' is an anagram indicator.
'more positive' becomes 'surer' ('sure' can be similar in meaning to 'positive').
'rate' is an anagram of 'trea'.
'trea'+'surer'='TREASURER'
'makes' acts as a link.
Can you help me to learn more?
(Other definitions for treasurer that I've seen before include "Official in charge of funds" , "position in society?" , "Book-keeper" , "who's got hold of the cash?" , "one safeguarding funds" .)