Bomb soaring over entrance to Russian fortress (8)
I believe the answer is:
garrison
'fortress' is the definition.
(I've seen this before)
'bomb soaring over entrance to russian' is the wordplay.
'bomb' indicates an anagram (I've seen 'bombed' mean this).
'over' is an insertion indicator.
'entrance to' suggests taking the first letters.
The initial letter of 'russian' is 'r'.
'soaring' with letters rearranged gives 'garison'.
'garison' going around 'r' is 'GARRISON'.
(Other definitions for garrison that I've seen before include "Troops stationed in a town to defend it" , "Soldiers in town" , "An armed force - or its location" , "(Soldiers guarding) fortified place" , "troops in base" .)