One's silly to accept portal entry initials with identical password (4,6)
I believe the answer is:
open sesame
'password' is the definition.
(Ali Baba and the Forty Thieves password)
'one's silly to accept portal entry initials with identical' is the wordplay.
'silly' indicates an anagram.
'to accept' indicates putting letters inside.
'initials' indicates taking the first letters.
'with' means one lot of letters go next to another.
'identical' becomes 'same' (similar in meaning).
The initial letters of 'portal entry' is 'pe'.
'ones' is an anagram of 'onse'.
'onse' enclosing 'pe' is 'opense'.
'opense'+'same'='OPEN SESAME'
(Other definitions for open sesame that I've seen before include "Spell from Ali Baba and the Forty Thieves" , "free entry" , "Spell unlocking doors" , "Magic password" , "Words of Ali Baba" .)