Controlled animal's lair after purge (6)
I believe the answer is:
ridden
'controlled' is the definition.
('ridden' can be similar in meaning to 'controlled')
'animal's lair after purge' is the wordplay.
'animal's lair' becomes 'den' (I've seen this before).
'after' means one lot of letters go next to another.
'purge' becomes 'rid' (I've seen this in other clues).
'den' after 'rid' is 'RIDDEN'.
(Other definitions for ridden that I've seen before include "What horses often are" , "(Of horse) mounted" , "Oppressed" , "Used for transport" , "(Of a horse) sat upon" .)