Amphibian, looking angry unfortunately, about to devour fellow (10)
I believe the answer is:
salamander
'amphibian' is the definition.
(I know that salamander is a type of amphibian)
'looking angry unfortunately about to devour fellow' is the wordplay.
'looking angry' becomes 'red' (red-faced).
'unfortunately' becomes 'alas' ('alas' is used to express regret).
'about' shows that the letters should be reversed in order.
'to devour' indicates putting letters inside (inserted letters are swallowed or devoured).
'fellow' becomes 'man' (fellow can mean a man).
'red'+'alas'='redalas'
'redalas' backwards is 'salader'.
'salader' going around 'man' is 'SALAMANDER'.
(Other definitions for salamander that I've seen before include "Lizard-like creature" , "amphibious creature" , "poker" , "An amphibian; fire spirit" , "Long-tailed amphibian" .)