Cheer for revolution in Teheran (7)

I believe the answer is:

hearten

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'cheer' is the definition.
(synonyms)

'revolution in teheran' is the wordplay.
'teheran' can be anagrammed to 'HEARTEN'.
However, I'm not clear how the anagram is indicated.

'for' is the link.

Can you help me to learn more?

(Other definitions for hearten that I've seen before include "Be encouraged" , "giving cheer" , "Encourage in Teheran" , "Make (someone) more confident" , "Buoy" .)

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