29 across
Hear
about
one
record
in
a
set
of
three
(7)
Hear about one record in a set of three (7)
hints
0
checks
0
hints
The definition is at the end of the clue.
How the clue works
Right, so a set of three is your definition, pointing to TRILOGY. For the wordplay, TRY is 'hear' (like a court trying a case), and it goes 'about' — meaning it wraps around — I standing for 'one' plus LOG standing for 'record', so you get TR, then I, then LOG, then Y, all slotted together into TRILOGY.