Western snakes and insects (5)
I believe the answer is:
wasps
'insects' is the definition.
(wasp is a kind of insect)
'western snakes' is the wordplay.
'western' becomes 'w'.
'snakes' becomes 'asps' (asp is a kind of snake).
'w'+'asps'='WASPS'
'and' acts as a link.
(Other definitions for wasps that I've seen before include "Rugby club" , "Insects; rugby union team" , "Ones playing together" , "Members of rugby team" , "Striped stinging insects" .)