Steel affected by poor weather (5)
I believe the answer is:
sleet
'poor weather' is the definition.
'sleet' can be an answer for 'weather' (sleet is a kind of weather). I am unsure of the 'poor' bit.
'steel affected' is the wordplay.
'affected' indicates an anagram.
'steel' anagrammed gives 'SLEET'.
'by' acts as a link.
Can you help me to learn more?
(Other definitions for sleet that I've seen before include "Mixed rain and melting snow" , "Precipitate evolution" , "Partly melted falling snow or hail" , "Partly frozen rain" , "Rain/ice mix" .)