Mask at one time put in cradle regularly (7)
I believe the answer is:
conceal
'mask' is the definition.
(mask can mean to conceal or hide)
'one time put in cradle regularly' is the wordplay.
'one time' becomes 'once' (synonyms).
'put in' indicates putting letters inside.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
The alternate letters of 'cradle' are 'cal'.
'once' put into 'cal' is 'CONCEAL'.
'at' acts as a link.
(Other definitions for conceal that I've seen before include "'Hide, keep secret (7)'" , "Hide, cover" , "hush up!" , "Keep out of sight" , "Screen" .)