Postman Pat has this wild animal biting villagers, primarily! (7)

'postman pat has this' is the definition.
(Postman Pat drives a van)

'wild animal biting villagers primarily' is the wordplay.
'wild' indicates an anagram.
'biting' is an insertion indicator (some letters bite or swallow others).
'primarily' suggests taking the first letters.
The first letter of 'villagers' is 'v'.
'animal' with letters rearranged gives 'mailan'.
'mailan' going around 'v' is 'MAILVAN'.