Burn evil American company! (5)
I believe the answer is:
singe
'burn' is the definition.
(singe is a kind of burn)
'evil american company' is the wordplay.
'evil' becomes 'sin' (synonyms).
'american company' becomes 'ge' (I can't explain this - if you can you should give a lot more credence to this answer).
'sin'+'ge'='SINGE'
Can you help me to learn more?
(Other definitions for singe that I've seen before include "Result of match accident" , "Superficial burn" , "Burn the ends or edges of" , "Result of burning" , "Earnest entreaty" .)