Bones initially needed in experiment to do with teaching (9)
I believe the answer is:
doctrinal
'to do with teaching' is the definition.
(to do with religious doctrines)
'bones initially needed in experiment' is the wordplay.
'bones' becomes 'doc' (I've seen this before).
'initially' indicates taking the first letters.
'in' is an insertion indicator.
'experiment' becomes 'trial' (trial is a kind of experiment).
The initial letter of 'needed' is 'n'.
'n' going into 'trial' is 'trinal'.
'doc'+'trinal'='DOCTRINAL'
(Another definition for doctrinal that I've seen is " Relating to beliefs".)