Beat time — mean to keep it (5)
I believe the answer is:
'beat' is the definition.
(basting is a kind of beating)
'mean to keep it' is the wordplay.
'mean' becomes 'base' ('base' can be a synonym of 'mean').
'to keep' is an insertion indicator.
'it' becomes 't' (abbreviation. e.g. in 'tis).
'base' going around 't' is 'BASTE'.
'time' is the link.
(Other definitions for baste that I've seen before include "Keep moist" , "Moisten with liquid fat while roasting" , "Sew" , "put on fat" , "clobber" .)