Look flushed and keep badgering on return (6)
I believe the answer is:
gander
'look' is the definition.
(informal term for a look or glance)
'flushed and keep badgering on return' is the wordplay.
'flushed' becomes 'red' (synonyms).
'and' says to put letters next to each other.
'keep badgering' becomes 'nag' (I can't justify this - if you can you should believe this answer much more).
'on return' says the letters should be written backwards.
'red'+'nag'='rednag'
'rednag' written backwards gives 'GANDER'.
Can you help me to learn more?
(Other definitions for gander that I've seen before include "male member of the Anatidae family" , "Male goose; look (colloq.)" , "waterbird" , "Glimpse" , "Ranged over the bird" .)