Model set to portray one of Zeus’s lovers in play? (7)
I believe the answer is:
diorama
'model set' is the definition.
'one of zeus's lovers in play?' is the wordplay.
'one of zeus's lovers' becomes 'io' (Greek myth).
'in' indicates putting letters inside.
'play?' becomes 'drama' ('drama' can be a synonym of 'play'**).
'io' going into 'drama' is 'DIORAMA'.
'to portray' acts as a link.
(Other definitions for diorama that I've seen before include "display" , "Miniature scene with figures" , "3-D model representing a scene" , "Representation of scene" , "model of the set" .)