What gun-runners take part in? (4,4)
I believe the answer is:
arms race
'in?' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'what gun-runners take part' is the wordplay.
I cannot quite see how this works, but
'gun' could be 'arm' (I've seen this in other clues) and 'arm' is present in the answer.
'take' could be 'r' (abbreviation for 'recipe', Latin for 'take') and 'r' is found in the answer.
'part' could be 'sac' (sac is a kind of part) and 'sac' is located in the leftover letters.
A single letter 'e' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for arms race that I've seen before include "military competition" , "rush to war" , "Potentially dangerous competition" , "A hostile international competition" , "dangerous situation escalating" .)