Stay with reactionary American while away (7)
I believe the answer is:
suspend
'stay' is the definition.
(I've seen this before)
'with reactionary american while away' is the wordplay.
'with' says to put letters next to each other.
'reactionary' shows that the letters should be reversed in order (reactions happen in the opposite direction).
'american' becomes 'us'.
'while away' becomes 'spend' (I've seen this before).
'us' written backwards gives 'su'.
'su'+'spend' is 'SUSPEND'.
(Other definitions for suspend that I've seen before include "put on line" , "Sends up (anag)" , "Delay" , "Adjourn" , "Temporarily render inoperative" .)