All there for the opening, we're told (5)
I believe the answer is:
whole
'all there' is the definition.
(I've seen this in another clue)
'opening we're told' is the wordplay.
'opening' becomes 'hole' (hole is a kind of opening).
'we're told' indicates a 'sounds like' (homophone) clue.
'hole' is a homophone of 'WHOLE'.
'for the' is the link.
(Other definitions for whole that I've seen before include "In entirety" , "Integral" , "Total" , "Entire, undivided" , "undamaged" .)