Buried shot inside stronghold (6)
I believe the answer is:
forgot
'buried' is the definition.
('forget' can be a synonym of 'bury')
'shot inside stronghold' is the wordplay.
'shot' becomes 'go' (I've seen this in other clues**).
'inside' is an insertion indicator.
'stronghold' becomes 'fort' (I've seen this before).
'go' inserted into 'fort' is 'FORGOT'.
(Other definitions for forgot that I've seen before include "Failed to recall" , "Left behind" , "Failed to remember" .)