Birds, some we see going backwards? (5)
I believe the answer is:
geese
'birds' is the definition.
(goose is a kind of bird)
'some we see going backwards?' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'backwards?' says the letters should be written in reverse (I've seen 'backwards' mean this).
'eseeg' can be found hidden inside 'we see going'.
'eseeg' in reverse letter order is 'GEESE'.
(Other definitions for geese that I've seen before include "Birds; silly people" , "Protectors of city" , "Water birds related to ducks and swans" , "0 Water birds" , "Farmyard creatures" .)