Reptiles get bad press biting man's head off (8)
I believe the answer is:
serpents
'reptiles' is the definition.
(serpent is a kind of reptile)
'bad press biting man's head off' is the wordplay.
I cannot quite see how this works, but
'man' could be 'pen' and 'pen' is found within the answer.
This may be the basis of clue (or it may be nonsense).
'get' acts as a link.
(Other definitions for serpents that I've seen before include "Presents of snakes" , "Unscrupulous people" , "Snakes or treacherous persons" , "Scaly reptiles" , "Dragons" .)