Date over, crystal clear? (3-7)
I believe the answer is:
see through
'crystal clear?' is the definition.
(thesaurus)
'date over' is the wordplay.
'date' becomes 'see' (synonyms).
'over' becomes 'through' (both can mean finished).
'see'+'through'='SEE-THROUGH'
(Other definitions for see through that I've seen before include "not be taken in" , "Stay to the end" , "thin clothes" , "sheer?" , "Transparent" .)