Call a limit (4)
I believe the answer is:
term
This clue is a double definition.
'call' is the first definition.
(to term something is to call it something)
'a limit' is the second definition.
(I've seen this before)
(Other definitions for term that I've seen before include "Period of school life" , "Name" , "Time spent at school" , "Hilary, in a > word" , "sentence?" .)