Avoid pies not awfully good to masticate! (6)
I believe the answer is:
eschew
'avoid' is the definition.
(eschewing is a kind of avoiding)
'to masticate' is the wordplay.
'to' becomes 'es' (I am not sure about this - if you are sure you should believe this answer much more).
'masticate' becomes 'chew' (synonyms).
'es'+'chew'='ESCHEW'
'pies not awfully good' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for eschew that I've seen before include "Abstain from (an activity)" , "'Avoid, stay away from (6)'" , "Deliberately stay clear of" , "Abstain from, shun" , "Avoid, abstain from (lit.)" .)