Doctor is required in harmful weather (7)
I believe the answer is:
drought
'harmful weather' is the definition.
(water shortage)
'doctor is required' is the wordplay.
'doctor' becomes 'Dr' (abbreviation).
'is required' becomes 'ought' (if you ought to do something you're required to).
'dr'+'ought'='DROUGHT'
'in' acts as a link.
(Other definitions for drought that I've seen before include "Lack of rainfall" , "Hot drug (anag)" , "Lack of rain" , "Severe water shortage" , "Period of abnormal dryness" .)