Bishop abandoning fanatical attack (4)
I believe the answer is:
raid
'attack' is the definition.
(raid is a kind of attack)
'bishop abandoning fanatical' is the wordplay.
'bishop' becomes 'B' (chess abbreviation).
'abandoning' is a deletion indicator.
'fanatical' becomes 'rabid' (synonyms).
'rabid' with 'b' taken out is 'RAID'.
(Other definitions for raid that I've seen before include "Sally" , "Rapid surprise attack" , "Inroad" , "Stock Exchange activity" , "Foray, sudden attack" .)