Two boys like Henry VIII, say (5)
I believe the answer is:
royal
'like henry viii say' is the definition.
(Henry VIII was royalty)
'two boys' is the wordplay.
'two boys' can mean two replacements for 'boy'.
'boy' becomes 'roy' ().
'boy' becomes 'Al'.
'roy'+'al'='ROYAL'
(Other definitions for royal that I've seen before include "- blue; - assent" , "Member of ruling family" , "August" , "Relating to a sovereign" , "complete" .)