Cold war aftermath? Tough to secure outright victory on retreating! (7,6)
I believe the answer is:
nuclear winter
'cold war aftermath?' is the definition.
'nuclear winter' can be an answer for 'aftermath?' (I have seen 'aftermath of war' mean 'nuclear winter' so perhaps 'aftermath' could also mean 'nuclear winter'). I'm not certain of the 'cold war' bit.
'tough to secure outright victory on retreating' is the wordplay.
I cannot quite understand how this works, but
'secure' could be 'win' (I've seen this in other clues) and 'win' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for nuclear winter that I've seen is " Atomic war aftermath".)