Looked angry as flag finally taken down (8)
I believe the answer is:
glowered
'looked angry' is the definition.
(I've seen this in another clue)
'flag finally taken down' is the wordplay.
'finally' suggests the final letters.
'taken down' becomes 'lowered' ('lower' can be a synonym of 'take down').
The final letter of 'flag' is 'g'.
'g'+'lowered'='GLOWERED'
'as' is the link.
(Other definitions for glowered that I've seen before include "Showed disapproval" , "Stared angrily" , "Looked furious" , "Scowled" .)