Summon boy attendant (4)
I believe the answer is:
page
This clue is a double definition.
'summon' is the first definition.
(paging is a kind of summoning)
'boy attendant' is the second definition.
(I've seen this before)
(Other definitions for page that I've seen before include "Attendant - sheet" , "Kind of leaf, or boy in old court" , "Leaf of book or boy servant" , "Boy attendant; send out call for" , "Leaf of book etc" .)