Play-act (7)
I believe the answer is:
pretend
I believe this clue is a double definition.
'play' is the first definition.
(pretending is a kind of playing)
'act' is the second definition.
(I know that act can be written as pretend)
(Other definitions for pretend that I've seen before include "Behave unnaturally" , "bluff" , "Sham" , "Simulate - make up" , "Imagined" .)