Somewhat roguish? One's totally trustworthy! (6)
I believe the answer is:
honest
'trustworthy' is the definition.
(similar in meaning)
'somewhat roguish? one's totally' is the wordplay.
'somewhat' indicates the answer is hidden within the clue.
'HONEST' is hidden in the letters of 'roguish ones totally'.
(Other definitions for honest that I've seen before include "Fair and just, not crooked" , "Honourable, true" , "Not disposed to cheat" , "Without dissimulation or guile" , "Reliable - the son (anag)" .)