Scold a busy fellow for hiding a deserter (6)
I believe the answer is:
berate
'scold' is the definition.
(synonyms)
'a busy fellow for hiding a deserter' is the wordplay.
'a busy fellow for' becomes 'bee' (I can't justify this - if you can you should believe this answer much more).
'hiding' means one lot of letters goes inside another.
'a deserter' becomes 'rat' (both can mean a traitor).
'bee' going around 'rat' is 'BERATE'.
Can you help me to learn more?
(Other definitions for berate that I've seen before include "Scold, castigate" , "Scold or chide severely" , "Scold, censure" , "Rebuke" , "Scold about rebate" .)