As a rule, it heartens the foreigner (5)

I believe the answer is:

reign

I'm a little stuck... Click here to teach me more about this clue!

'as a rule' is the definition.
(I've seen this before)

'it heartens the foreigner' is the wordplay.
'REIGN' is hidden within the letters.
But, I'm not sure how this is indicated.

Can you help me to learn more?

(Other definitions for reign that I've seen before include "Wield the sceptre" , "Time on throne" , "Sit on a throne" , "Period during which someone is dominant" , "Hold sway, rule" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app