Software to facilitate calm (7)
I believe the answer is:
appease
'calm' is the definition.
(appeasing is a kind of calming)
'software to facilitate' is the wordplay.
'software' becomes 'app' (software application).
'to facilitate' becomes 'ease' ('ease' can be a synonym of 'facilitate').
'app'+'ease'='APPEASE'
(Other definitions for appease that I've seen before include "Quiet" , "Calm, pacify, placate" , "Placate by giving in to demands" , "Mollify or calm by making concessions" , "be satisfying" .)