Slender and delicate wife leaves game (1,3)
I believe the answer is:
i spy
'game' is the definition.
(I Spy is a guessing game)
'slender and delicate wife leaves' is the wordplay.
'slender and delicate' becomes 'wispy' (I've seen this before).
'wife' becomes 'w' (abbreviation).
'leaves' is a deletion indicator.
'wispy' with 'w' taken away is 'I-SPY'.
(Other definitions for i spy that I've seen before include "One ac's [BOND] admission" , "looking game" , "I spot" , "admission by Mata Hari?" , "Game played with young children" .)