Person regularly needing rope to control alien mob (11)
I believe the answer is:
proletariat
'mob' is the definition.
(thesaurus)
'person regularly needing rope to control alien' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'needing' is a charade indicator (letters next to each other).
'rope' becomes 'lariat' (lariat is a kind of rope).
'to control' is an insertion indicator.
'alien' becomes 'et' (extra terrestrial).
The alternate letters of 'person' are 'pro'.
'lariat' enclosing 'et' is 'letariat'.
'pro'+'letariat'='PROLETARIAT'
(Other definitions for proletariat that I've seen before include "Working-class people" , "The lower orders" , "The people; workers" , "The working class" , "Marx's wage-earning class" .)