Trouble at start of career (4)
I believe the answer is:
care
This could be a double definition.
'trouble' is the first definition.
(thesaurus)
'start of career' is the second definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'at' is the link.
Can you help me to learn more?
(Other definitions for care that I've seen before include "Prudence" , "Happy-go-lucky" , "Have concern or regard" , "Protective custody" , "Race (anag.)" .)