No expert, but someone of a mature disposition (7)

I believe the answer is:

amateur

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

'no expert' is the definition.
(I've seen this in another clue)

'someone of a mature disposition' is the wordplay.
'a mature' anagrams to 'AMATEUR'.
Though, I'm unsure how the anagram is indicated.

'but' acts as a link.

Can you help me to learn more?

(Other definitions for amateur that I've seen before include "Not pro" , "Non-pro" , "he's not making any money" , "Unpaid (sport)" , "hobbyist" .)

I've seen this clue in The Irish News.

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