Bristle now with anger initially, flipping (3)
I believe the answer is:
awn
'bristle' is the definition.
(botanical term)
'now with anger initially flipping' is the wordplay.
'initially' says to take the initial letters.
'flipping' shows that the letters should be reversed in order.
The first letters of 'now with anger' is 'nwa'.
'nwa' backwards is 'AWN'.
(Other definitions for awn that I've seen before include "Stiff bristle on grasses" , "Bristle on cereal spike" , "Beard of plant" , "Bristly head of barley sheath, quite wan" , "Bristle-like appendage on grass" .)