Screen previously in California (7)
I believe the answer is:
conceal
'screen' is the definition.
(I've seen this before)
'previously in california' is the wordplay.
'previously' becomes 'once' (once means in the past).
'in' is an insertion indicator.
'california' becomes 'cal' (short for California).
'once' going into 'cal' is 'CONCEAL'.
(Other definitions for conceal that I've seen before include "Screen" , "hush up!" , "'Hide, keep secret (7)'" , "Keep out of sight" , "Place out of sight" .)