Stop a minister returning on time (5)
I believe the answer is:
avert
'stop' is the definition.
(thesaurus)
'a minister returning on time' is the wordplay.
'minister' becomes 'rev' (I've seen this before**).
'returning' shows that the letters should be reversed in order.
'on' means one lot of letters go next to another.
'time' becomes 't'.
'rev' back-to-front is 'ver'.
'a'+'ver'+'t'='AVERT'
(Other definitions for avert that I've seen before include "Turn away from, say gaze" , "Turn aside, perhaps gaze" , "Stop" , "Avoid" , "Ward off, deflect" .)