Instinctive to cover fellow’s opening in nearby armed battle (8)
I believe the answer is:
gunfight
'battle' is the definition.
(I know that gunfight is a type of combat)
'instinctive to cover fellow's opening in nearby' is the wordplay.
'instinctive' becomes 'gut' (as in a gut feeling).
'to cover' is an insertion indicator.
'opening' says to take the initial letters.
'in' means one lot of letters goes inside another.
'nearby' becomes 'nigh' (I've seen this before).
The first letter of 'fellows' is 'f'.
'f' inserted into 'nigh' is 'nfigh'.
'gut' going around 'nfigh' is 'GUNFIGHT'.
'armed' acts as a link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for gunfight that I've seen before include "Shoot-out (at the OK Corral?)" , "Battle in Westerns" , "There was one at the O.K. Corral" , "At which Wyatt Earp broke the Clanton gang" , "Showdown at the OK Corral" .)