Force rascal to perform (6)
I believe the answer is:
impact
'force' is the definition.
(impacting is a kind of forcing)
'rascal to perform' is the wordplay.
'rascal' becomes 'imp' ('imp' can be a synonym of 'rascal').
'to perform' becomes 'act' (acting is a kind of performing).
'imp'+'act'='IMPACT'
(Other definitions for impact that I've seen before include "The force of one body against another" , "Force or shock of a collision" , "Force exerted by collision" , "Repercussion" , "Marked effect; hit" .)