Emotion that is dangerous? Not entirely (5)
I believe the answer is:
anger
'emotion' is the definition.
(anger is an emotion)
'dangerous? not entirely' is the wordplay.
'not entirely' says the answer is hidden in the clue.
'ANGER' can be found hidden inside 'dangerous'.
'that is' is the link.
(Other definitions for anger that I've seen before include "Wrath, fury" , "Spleen" , "Hot displeasure; enrage" , "Irateness" , "Hack off" .)