Healthy range of food for tightrope walker? (8,4)

I believe the answer is:

balanced diet

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

'tightrope walker?' is the definition.
Both the answer and definition are singular nouns.
Perhaps they are linked in a way I don't understand?

'healthy range of food' is the wordplay.
'healthy range of' becomes 'balanced' (I can't explain this - if you can you should believe this answer much more).
'food' becomes 'diet' (diet is a kind of food).
'balanced'+'diet'='BALANCED DIET'

'for' acts as a link.

Can you help me to learn more?

I've seen this clue in The Daily Express.

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