Raise cube enclosed by layer (8)
I believe the answer is:
heighten
'raise' is the definition.
(I know that raise can be written as heighten)
'cube enclosed by layer' is the wordplay.
'cube' becomes 'eight' (8 is a cube number).
'enclosed by' means one lot of letters goes inside another.
'layer' becomes 'hen' (something which lays - eggs in this case).
'eight' inserted within 'hen' is 'HEIGHTEN'.
(Other definitions for heighten that I've seen before include "Intensify; make taller" , "Intensify, enhance" , "Raise" , "Elevate - intensify" , "Increase in amount of degree" .)