Fly solo over diminishing country steeped in history (2,2,5)
I believe the answer is:
go it alone
'fly solo' is the definition.
(I've seen this in another clue)
'over diminishing country steeped in history' is the wordplay.
I cannot quite understand how this works, but
'over' could be 'on' (physically on top of) and 'on' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for go it alone that I've seen before include "Take something on, eschewing any help" , "act unaided" , "Proceed without the help of others" , "Act on one's own" , "Act independently" .)