Conventional hot rod customised to break circuit times (8)
'conventional' is the definition.
(similar in meaning)
'hot rod customised to break circuit times' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'hot' is 'tho' which is within the answer.
an anagram of 'rod' is 'ord' which is present in the remaining letters.
'circuit' could be 'o' and 'o' is located in the answer.
'times' could be 'x' (multiplication sign) and 'x' is located in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for orthodox that I've seen before include "Conforming to the accepted beliefs of a religion", "straight", "Adhering to doctrine", "Conforming with established doctrine", "Conforming with tradition".)