25 across
Following
one
action
of
union,
embracing
it
(9)
Following one action of union, embracing it (9)
hints
0
checks
0
hints
The definition is at the beginning of the clue.
How the clue works
The definition is Following, in the sense of copying or mimicking. For the wordplay, take I (one), then MATING (action of union), and slot IT inside it (embracing it), giving you I + M-IT-ATING.