Tricky maths that could be a pain to pass (8)
I believe the answer is:
calculus
'tricky maths' is the definition.
'calculus' can be an answer for 'maths' (calculus is a kind of maths). I am unsure of the 'tricky' bit.
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for calculus that I've seen before include "System of mathematical computation (often differential)" , "Maths dealing with rates of variation" , "method of reasoning" , "Branch of maths dealing with differentiation and integration" , "Branch of mathematics developed by Newton and Leibnitz" .)