They're a bit fed up, especially as they've been tricked (5)
I believe the answer is:
dupes
'they've been tricked' is the definition.
I can't judge whether this defines the answer.
'they're a bit fed up especially' is the wordplay.
'DUPES' is hidden within the letters.
However, I am not sure how the hidden word is indicated.
'as' is the link.
Can you help me to learn more?
(Other definitions for dupes that I've seen before include "Gulls" , "Fools, deceives" , "Fools, hoaxes" , "Hoodwinks" , "Cheats" .)