Positioned like a king in charge of subject (5)
I believe the answer is:
topic
'subject' is the definition.
(as in a topic for discussion)
'positioned like a king in charge' is the wordplay.
I cannot really see how this works, but
'in charge' could be 'ic' (abbreviation for 'in charge') and 'ic' is found within the answer.
The remaining letters 'top' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'of' acts as a link.
Can you help me to learn more?
(Other definitions for topic that I've seen before include "That may be debatable" , "might this be hot?" , "Something to discuss" , "Question" , "Subject (of, eg, speech)" .)