Detest bowler, perhaps — and Essex opener! (4)
I believe the answer is:
hate
'detest' is the definition.
(synonyms)
'bowler perhaps and essex opener' is the wordplay.
'bowler perhaps' becomes 'hat' (bowler is a kind of hat).
'and' is a charade indicator (letters next to each other).
'opener' suggests taking the first letters.
The first letter of 'essex' is 'e'.
'hat'+'e'='HATE'
(Other definitions for hate that I've seen before include "Dislike intensely" , "Strong aversion" , "Detest" , "Loathing" , "Passion" .)