Old Iberians regularly rise late (3,2)
I believe the answer is:
lie in
'rise late' is the definition.
(I've seen this before)
'old iberians regularly' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'old'+'iberians'='oldiberians'
The alternate letters of 'oldiberians' are 'LIE-IN'.
(Other definitions for lie in that I've seen before include "An extra spell in bed" , "Extended bedtime!" , "An extended stay in bed" , "Make a late start" , "Protracted stay in bed" .)