Crossword Genius

At various distances, per distance respecified? (11)

Ross

I believe the answer is:

interspaced

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

'at various distances' is the definition.
I can't judge whether this defines the answer.

'per distance respecified?' is the wordplay.
'per distance' anagrams to 'INTERSPACED'.
But, I am unsure how this is indicated.

Can you help me to learn more?

I've seen this clue in The Independent.
Want a hint initially instead of a full solution? Install my app