This crossword has normal clues. Only one crossing letter need be changed before entry.
I am stuck with last few .
12a. Over 50s group visiting college promises to be perceptive (9)
Is sagacious correct?
7d
After counting sheep does he dream of live ones? (7)
A?????d
19d Measure of the frequency of some small birds?(7)
N?t?a??
12 sagacious saga = over 50s group c = college ious = promises
7 android = from a book title something like 'Do androids dream of counting electric sheep?'