Westbound vampires making attempt (4)
I believe the answer is:
stab
'attempt' is the definition.
(to have a stab is to attempt something)
'westbound vampires' is the wordplay.
'westbound' shows that the letters should be reversed in order (letters written from right to left).
'vampires' becomes 'bats' (I've seen this in another clue).
'bats' reversed gives 'STAB'.
'making' is the link.
(Other definitions for stab that I've seen before include "Wound with a dagger" , "effort" , "Sudden sharp pain" , "Impale; attempt" , "Sudden sharp feeling" .)