Dominating (5)
'dominating' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for bossy that I've seen before include "Informally overbearing and imperious" , "Disagreeably domineering" , "Domineering (colloq.)" , "Autocratic" , "authoritarian" .)
(Another definition for ontop that I've seen is " Leading".)
(Other definitions for on top that I've seen before include "In a dominant position" , "Winning" , "Leading" , "At the summit or in superior position" .)
'dominating' is the definition.
('rule' can be a synonym of 'dominate')
This is all the clue.
(Other definitions for ruling that I've seen before include "Authoritative decision" , "Drawing a fine line" , "Judgement" , "Verdict" , "Judge's decision" .)