Natural opener not opening with the others (2,2)
I believe the answer is:
et al
'with the others' is the definition.
('et al' means 'and others' in Latin)
'natural opener not opening' is the wordplay.
'natural opener' becomes 'petal' (part of a flower which opens up).
'not opening' means to remove the first letter (the opening letter is removed).
'petal' with its initial letter removed is 'ET AL'.
(Other definitions for et al that I've seen before include "Latin notation - late for others" , "Latin abbreviation meaning 'and others'" , "And the rest (Lat. abbr.)" , "... and other people (or things) (abbr)" , "And the rest, to the old Romans" .)