Hint in straightforward manner: Leader must go (5)
I believe the answer is:
imply
'hint' is the definition.
(thesaurus)
'in straightforward manner leader must go' is the wordplay.
'in straightforward manner' becomes 'simply'.
'leader must go' means to remove the first letter.
'simply' with its first letter taken off is 'IMPLY'.
(Other definitions for imply that I've seen before include "Express by indirect means" , "Hint, suggest" , "Insinuate, hint" , "Mean" , "Involve - intimate" .)