Caught in elaborate ruse, both coming back of course (2,2,4)
I believe the answer is:
to be sure
'of course' is the definition.
(thesaurus)
'caught in elaborate ruse both coming back' is the wordplay.
'caught in' indicates a hidden word.
'coming back' says the letters should be written backwards.
'erusebot' is hidden in the letters of 'elaborate ruse both'.
'erusebot' written backwards gives 'TO BE SURE'.
(Other definitions for to be sure that I've seen before include "Without doubt" , "Admittedly" , "Of course, certainly" , "I admit" , "Undoubtedly" .)