A warm spell centrally then storms -- he might say that (10)
I believe the answer is:
weatherman
'he might say that' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'a warm spell centrally then storms' is the wordplay.
'centrally' indicates the central letters.
'storms' is an anagram indicator.
The middle letter of 'spell' is 'e'.
'a'+'warm'+'e'+'then'='awarmethen'
'awarmethen' is an anagram of 'WEATHERMAN'.
Can you help me to learn more?
(Other definitions for weatherman that I've seen before include "TV forecaster" , "Met fellow" , "He provides forecasts" , "Fish possibly once" , "Met worker" .)