Term is used as title (6)
I believe the answer is:
mister
'title' is the definition.
(I know that Mister is a type of title)
'term is used' is the wordplay.
'used' is an anagram indicator.
'term'+'is'='termis'
'termis' anagrammed gives 'MISTER'.
'as' is the link.
(Other definitions for mister that I've seen before include "that's what you'd call him" , "Form of address to a man, used without his name" , "Merits of form of address to man" , "Male form of address" , "Mr" .)