Ask to be at the grand opening (3)
I believe the answer is:
beg
'ask' is the definition.
(begging is a kind of asking)
'be at the grand opening' is the wordplay.
'at' is a charade indicator (letters next to each other).
'opening' says to take the initial letters.
The first letter of 'grand' is 'g'.
'be'+'g'='BEG'
'to' is the link.
(Other definitions for beg that I've seen before include "Plead or scrounge" , "Plead like mendicant" , "Beseech or ask for charity" , "Solicit charity" , "Ask humbly" .)