Callers upset with Tracy? That's perfectly obvious (7-5)
I believe the answer is:
crystal-clear
'perfectly obvious' is the definition.
(crystal-clear means completely obvious)
'callers upset with tracy?' is the wordplay.
'upset with' indicates an anagram.
'callers' mixed up with 'tracy' makes 'CRYSTAL-CLEAR'.
'that's' is the link.
(Other definitions for crystal-clear that I've seen before include "Totally see-through" , "Absolutely evident" , "Completely unclouded" , "In need of no further explanation" , "Pellucid" .)