Cool line in rainwear turning up (4)
I believe the answer is:
calm
'cool' is the definition.
(I've seen this before)
'line in rainwear turning up' is the wordplay.
'line' becomes 'l' (used when specifying particular lines from a poem).
'in' means one lot of letters goes inside another.
'rainwear' becomes 'mac' (I am not sure about this - if you are sure you should believe this answer much more).
'turning up' says the letters should be written in reverse.
'l' inserted inside 'mac' is 'mlac'.
'mlac' reversed gives 'CALM'.
Can you help me to learn more?
(Other definitions for calm that I've seen before include "Still and quiet" , "'After a storm comes a ....'" , "Pacific" , "Tranquil, undisturbed" , "Still - force 0 on the Beaufort scale" .)