A royal son finally put in charge (6)
I believe the answer is:
prince
'a royal son' is the definition.
(I've seen this before)
'finally put in charge' is the wordplay.
I cannot really understand how this works, but
'in' is found in the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for prince that I've seen before include "King's son" , "Boxer Naseem Hamed's "title"" , "See 1" , "Possible future titular head" , "Machiavellian ruler" .)