Map line giving us a wintry promenade (4,5)
I believe the answer is:
cold front
'map line' is the definition.
The answer and definition can be both types of natural phenomena as well as being singular nouns.
Maybe there's an association between them I don't understand?
'a wintry promenade' is the wordplay.
'a wintry' becomes 'cold' (I've seen this in another clue).
'promenade' becomes 'front' (sea front).
'cold'+'front'='COLD FRONT'
'giving us' is the link.
Can you help me to learn more?
(Other definitions for cold front that I've seen before include "Meteorological boundary" , "which might change the weather" , "freeze?" , "that might bring on a chill" , "sometimes a feature of weather forecast" .)