Like birds initially imported in a commercial vehicle (5)
I believe the answer is:
avian
'like birds initially imported in a commercial vehicle' is the definition.
I can't judge whether this definition defines the answer.
'initially imported in a commercial vehicle' is the wordplay.
'initially' indicates taking the first letters.
'in' indicates putting letters inside.
'commercial vehicle' becomes 'van' (I've seen this before).
The first letter of 'imported' is 'i'.
'a'+'van'='avan'
'i' inserted within 'avan' is 'AVIAN'.
Can you help me to learn more?
(Other definitions for avian that I've seen before include "To do with birds - like a dangerous flu" , "Birdlike" , "Relating to birds" , "Pertaining to or characteristic of birds" , "Resembling a bird" .)