Attack burn, say, from the east (6)
I believe the answer is:
charge
'attack' is the definition.
(charging is a kind of attacking)
'burn say from the east' is the wordplay.
'burn' becomes 'char' (charring is a kind of burning).
'say' becomes 'eg'.
'from the east' is a reversal indicator.
'eg' backwards is 'ge'.
'char'+'ge'='CHARGE'
(Other definitions for charge that I've seen before include "Amount to pay - attack" , "Formally accuse; rush" , "Accuse or rush forward" , "Do as the Light Brigade did" , "Storm" .)