Angry being trapped into turning vegetarian (5)
I believe the answer is:
irate
'angry' is the definition.
('irate' can be similar in meaning to 'angry')
'being trapped into turning vegetarian' is the wordplay.
'turning' says the letters should be written in reverse.
'being trapped into' indicates the answer is hidden within the clue.
'etari' is hidden within 'vegetarian'.
'etari' in reverse letter order is 'IRATE'.
(Other definitions for irate that I've seen before include "A tier (anag)" , "I tear away, being annoyed" , "Annoyed, irritated" , "Wild" , "Not happy" .)