Former political leader seen in the Athenaeum (5)

I believe the answer is:

heath

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

'former political leader' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.

'in the athenaeum' is the wordplay.
'in' says the answer is hidden in the clue.
'HEATH' is hidden within 'the athenaeum'.

'seen' acts as a link.

Can you help me to learn more?

(Other definitions for heath that I've seen before include "Barren open land" , "Open uncultivated land" , "Tract of open land" , "Scrub" , "Moorland shrub" .)

I've seen this clue in The Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.