Mama had a thing about spiritual adviser (7,6)

I believe the answer is:

mahatma gandhi

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

'spiritual adviser' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps there's an association between them I don't understand?

'mama had a thing about' is the wordplay.
'about' indicates an anagram.
'mama'+'had'+'a'+'thing'='mamahadathing'
'mamahadathing' anagrammed gives 'MAHATMA GANDHI'.

Can you help me to learn more?

I've seen this clue in The Everyman puzzle in The Observer.

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