Record includes half of exam I pass prior to variable study of words (10)
I believe the answer is:
'study of words' is the definition.
(I've seen this before)
'record includes half of exam i pass' is the wordplay.
'record' becomes 'logy' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'includes' is an insertion indicator.
'half of' means to take half the letters.
'pass' becomes 'col' (col is a term for a mountain pass).
'exam' cut in half is 'ex'.
'logy' placed around 'exicol' is 'LEXICOLOGY'.
'prior to variable' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Another definition for lexicology that I've seen is " Study of words".)