23 across
Figure
set
around
mostly
satisfactory
constant
(6)
Figure set around mostly satisfactory constant (6)
hints
0
checks
0
hints
The definition is at the beginning of the clue.
How the clue works
The definition is Figure, cluing a number with twelve digits' worth of letters. You've got set giving you TV (a television set), wrapped around mostly satisfactory — that's WELL with its last letter chopped off, so WEL — and then constant tacks on E (the mathematical one) at the end.