Brooding about god (4)
I believe the answer is:
odin
'god' is the definition.
(Norse god)
'brooding about' is the wordplay.
'about' indicates the answer is hidden within the clue (the clue goes around or about the answer).
'ODIN' can be found hidden inside 'brooding'.
(Other definitions for odin that I've seen before include "mythological personage" , "Mythological Norse god of war" , "God - I nod (anag)" , "Pagan god" , "Supreme god of Scandanavian myth" .)