Dull experts and flipping spies (7)
I believe the answer is:
prosaic
'dull' is the definition.
(similar in meaning)
'experts and flipping spies' is the wordplay.
'experts' becomes 'pros' (professionals).
'and' says to put letters next to each other.
'flipping' is a reversal indicator.
'spies' becomes 'CIA' (Central Intelligence Agency).
'cia' written backwards gives 'aic'.
'pros'+'aic'='PROSAIC'
(Other definitions for prosaic that I've seen before include "Lacking originality" , "routine" , "Poetry would not be so" , "boring!" , "Commonplace, unromantic" .)