Bowler possibly ending in ambulance can't stand (4)
I believe the answer is:
hate
'can't stand' is the definition.
(I've seen this in another clue)
'bowler possibly ending in ambulance' is the wordplay.
'bowler possibly' becomes 'hat' (bowler is a type of hat).
'ending in' indicates one should take the final letters.
The final letter of 'ambulance' is 'e'.
'hat'+'e'='HATE'
(Other definitions for hate that I've seen before include "Despise" , "Passion" , "Passionately dislike" , "Strongly dislike" , "Abhor" .)