Some bully in green being untruthful (5)
I believe the answer is:
lying
'untruthful' is the definition.
(similar in meaning)
'some bully in green' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'LYING' is hidden within 'bully in green'.
'being' acts as a link.
(Other definitions for lying that I've seen before include "dishonesty" , "Deceitful" , "telling stories" , "Prevaricating" , "Invention" .)