Walk like a penguin (6)
I believe the answer is:
waddle
'walk like a penguin' is the definition.
(penguins waddle)
This is the entire clue.
(Other definitions for waddle that I've seen before include "Duck-like walk" , "Walk, taking short steps, rocking from side to side" , "Walk like duck, fat man" , "Walk with clumsily swaying motion" , "Walk duck-fashion" .)