Opening puree, rat happy (8)
I believe the answer is:
aperture
'opening' is the definition.
(I know that aperture is a type of hole)
'puree rat happy' is the wordplay.
'happy' is an anagram indicator (happy can mean slightly drunk).
'puree'+'rat'='pureerat'
'pureerat' anagrammed gives 'APERTURE'.
(Other definitions for aperture that I've seen before include "Opening (on camera, for example)" , "Device controlling amount of light admitted" , "Eye" , "Opening, to let light enter a camera perhaps" , "Opening, mostly small" .)