He takes an age to get things under control (3)
I believe the answer is:
man
'he takes an age to get things under control' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he takes an' is the wordplay.
'he takes' becomes 'm' (I can't explain this - if you can you should believe this answer much more).
'm'+'an'='MAN'
Can you help me to learn more?
(Other definitions for man that I've seen before include "Male person" , "Isle of -; chess piece" , "Isle of ..., ... o'war" , "Soldier" , "Homo sapiens" .)