Straightforward, as in the old uprising (4)
I believe the answer is:
easy
'straightforward' is the definition.
(easy can mean straightforward or simple)
'as in the old uprising' is the wordplay.
'in' indicates putting letters inside.
'the old' becomes 'ye' (resembles a historical spelling of 'the').
'uprising' says the letters should be written in reverse.
'ye' written backwards gives 'ey'.
'as' going inside 'ey' is 'EASY'.
(Other definitions for easy that I've seen before include "Relaxed" , "... Rider (film)" , "careful!" , "Straightforward" , "Not challenging" .)