Pretend in practice (3)
I believe the answer is:
act
'pretend' is the definition.
(I've seen this in other clues)
'in practice' is the wordplay.
'in' says the answer is hidden in the clue.
'ACT' is hidden within 'practice'.
(Other definitions for act that I've seen before include "Major division of play" , "Start of a drama" , "performing group" , "turn" , "Thing done" .)