Wanted to include a couple of royals when necessary (9)
I believe the answer is:
warranted
'necessary' is the definition.
(warranted means justified or necessary)
'wanted to include a couple of royals' is the wordplay.
'to include' indicates putting letters inside.
'couple of' indicates the doubling of some letters.
'royals' becomes 'r' (this might be a standard abbreviation which I don't know about).
'r' doubled is 'rr'.
'a'+'rr'='arr'
'wanted' placed around 'arr' is 'WARRANTED'.
'when' is the link.
Can you help me to learn more?
(Another definition for warranted that I've seen is " Justified or guaranteed".)