Actuaries oddly missing fix (4)
I believe the answer is:
cure
'fix' is the definition.
(I know that cure is a more specific form of keep)
'actuaries oddly missing' is the wordplay.
'oddly missing' indicates alternate letters (letters in odd-numbered positions removed).
The alternate letters of 'actuaries' are 'CURE'.
(Other definitions for cure that I've seen before include "Parish priest in France" , "Make well again" , "Restore to health or preserve with salt" , "Restore to good health" , "Heal or pickle" .)