Follow on, say, in charge (5)
I believe the answer is:
segue
'follow on' is the definition.
(I've seen this before)
'say in charge' is the wordplay.
'say' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'in' indicates putting letters inside.
'charge' becomes 'sue' (as in suing somebody in court).
'eg' placed into 'sue' is 'SEGUE'.
(Other definitions for segue that I've seen before include "Keep going without interruption" , "Follow on seamlessly" , "carry on" , "Play on" , "Proceed immediately" .)