Cook keeps trying not to offend old trendy (6)
I believe the answer is:
hepcat
'offend old trendy' is the definition.
I can't judge whether this defines the answer.
'cook keeps trying not' is the wordplay.
'cook' becomes 'heat' (I've seen this before).
'keeps' means one lot of letters goes inside another (inserted letters are kept inside).
'trying not' becomes 'pc' (I can't explain this - if you can you should give a lot more credence to this answer).
'heat' going around 'pc' is 'HEPCAT'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for hepcat that I've seen before include "one with it" , "Jazz or swing fan (1940s' slang)" , "Old jazz fan" , "trendy no longer" .)