Walk like a duck at start of trip? Rubbish! (7)
I believe the answer is:
twaddle
'rubbish' is the definition.
(both can mean nonsense)
'walk like a duck at start of trip?' is the wordplay.
'walk like a duck' becomes 'waddle' (ducks waddle when they walk).
'at' is a charade indicator (letters next to each other) (I've seen this in other clues).
'start of' says to take the initial letters.
The first letter of 'trip' is 't'.
'waddle' after 't' is 'TWADDLE'.
(Other definitions for twaddle that I've seen before include "Trivial speech or writing" , "Moonshine" , "Foolish speech" , "Rubbish" , "Balderdash" .)