Father troubled about dull result (9)
I believe the answer is:
aftermath
'result' is the definition.
(aftermath is a kind of result)
'father troubled about dull' is the wordplay.
'troubled' indicates anagramming the letters.
'about' means one lot of letters goes inside another.
'dull' becomes 'mat' ('mat' can be similar in meaning to 'dull'**).
'father' anagrammed gives 'afterh'.
'afterh' placed around 'mat' is 'AFTERMATH'.
(Other definitions for aftermath that I've seen before include "Wake" , "Subsequent consequence" , "Circumstances that follow an event" , "Second crop" , "Circumstances that follow as a result of something" .)