The gamekeepers won't speak about it but it will come out. (6)
I believe the answer is:
emerge
'come out' is the definition.
(synonyms)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for emerge that I've seen before include "Become known or apparent" , "Come out or transpire" , "Come into greater prominence" , "Develop" , "Come out or become known" .)