Continue to think, having turned in, about (6)
I believe the answer is:
resume
'continue' is the definition.
(I know that resume is a more specific form of continue)
'think having turned in about' is the wordplay.
'think' becomes 'muse' (to muse on something is to think about it).
'having turned' says the letters should be written in reverse.
'in' means one lot of letters goes inside another.
'about' becomes 're' ('re' means regarding or about).
'muse' written backwards gives 'esum'.
'esum' placed into 're' is 'RESUME'.
'to' acts as a link.
(Other definitions for resume that I've seen before include "Abstract" , "Continue after interruption" , "Precis" , "Short descriptive summary" , "Go on after a pause" .)