About to enter bed and procreate (5)
I believe the answer is:
breed
'procreate' is the definition.
(breeding is a kind of procreating)
'about to enter bed' is the wordplay.
'about' becomes 're' (regarding).
'to enter' is an insertion indicator.
're' going into 'bed' is 'BREED'.
'and' acts as a link.
(Other definitions for breed that I've seen before include "Propagate; this happy one, Richard II" , "Special variety within a species" , "Livestock classification" , "Mate specific animals to produce certain qualities" , "Produce offspring, say horses" .)