Part of navy does, for example, around second besieged city (9)
I believe the answer is:
destroyer
'part of navy' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'does for example around second besieged city' is the wordplay.
'does for example' becomes 'deer' (I've seen this in another clue).
'around' indicates putting letters inside.
'second' becomes 's' (common abbreviation).
'besieged city' becomes 'Troy' (city besieged for ten years in Greek myth).
's'+'troy'='stroy'
'deer' going around 'stroy' is 'DESTROYER'.
Can you help me to learn more?
(Other definitions for destroyer that I've seen before include "HMS" , "Red oyster (anag)" , "Military vessel" , "Small, fast warship" , "Naval vessel" .)