Bullets etc found in moorhen's wings — God! (6)
I believe the answer is:
mammon
'god' is the definition.
(ancient fortune god)
'bullets etc found in moorhen's wings' is the wordplay.
'bullets etc' becomes 'ammo' (abbreviation for ammunition).
'found in' means one lot of letters goes inside another.
'wings' suggests removing the centre (the wings or edge letters of the word are used).
'moorhen' with its middle taken out is 'mn'.
'ammo' put within 'mn' is 'MAMMON'.
(Other definitions for mammon that I've seen before include "Greed personified" , "Wealth (worshipped)" , "money" , "False god of riches and greed" , "Wealth personified, you cannot serve God an . . . . . ." .)