A little creep unworthily about to tell the truth (3,2)
I believe the answer is:
own up
'tell the truth' is the definition.
(I've seen this in another clue)
'a little creep unworthily about' is the wordplay.
'a little' indicates a hidden word (a little bit of the clue).
'about' says the letters should be written in reverse.
'punwo' is hidden in the letters of 'creep unworthily'.
'punwo' reversed gives 'OWN UP'.
'to' is the link.
(Other definitions for own up that I've seen before include "Confess, acknowledge fault" , "Come clean (about wrongdoing)" , "Admit to wrongdoing" , "be honest" , "Accept responsibility" .)