Worry about American workers on strike, finally getting involved (9)
I believe the answer is:
elaborate
'involved' is the definition.
(thesaurus)
'worry about american workers on strike finally' is the wordplay.
'worry' becomes 'eat' (eating is a kind of worrying).
'about' is an insertion indicator.
'american workers' becomes 'labor' (US spelling of 'labour').
'on' means one lot of letters go next to another.
'strike finally' becomes 'e' (I can't explain this - if you can you should believe this answer much more).
'eat' placed around 'labor' is 'elaborat'.
'elaborat'+'e'='ELABORATE'
'getting' acts as a link.
(Other definitions for elaborate that I've seen before include "Complicated - complex" , "Detailed, complicated" , "Complicated, with many parts or details" , "Polish" , "Ostentatious, possibly" .)