Limit flexible term accommodated by Devon banker (7)
I believe the answer is:
extreme
'limit' is the definition.
(thesaurus)
'flexible term accommodated by devon banker' is the wordplay.
'flexible' indicates an anagram (I've seen this in other clues).
'accommodated by' means one lot of letters goes inside another.
'devon banker' becomes 'exe' (river - something with banks - in Devon).
'term' anagrammed gives 'trem'.
'trem' inserted into 'exe' is 'EXTREME'.
(Other definitions for extreme that I've seen before include "Utmost; excessive" , "Farthest - drastic" , "Farthest limit" , "Last" , "Exceptional - radical" .)