I'm an 8 letter word

Challenge for all masterminds!!
I'm An 8 Letter Word.
First 4 Is The Question,
2 3 4 Protects Our Head,
5 6 7 Is A Liquid In Tree
7 & 8 R Same Letters.
Who Am I ?

Click here for Answer

W H A T S A P P
WHAT = Question
HAT = Protects our head
SAP = Liquid in Tree
PP = Same Letters