As far as tides can possibly reach (8)

I believe the answer is:

distance

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

'reach' is the definition.
(thesaurus)

'as far as tides can' is the wordplay.
'tides can' can be anagrammed to 'DISTANCE'.
But, I'm not sure how the anagram is indicated.

'possibly' is the link.

Can you help me to learn more?

(Other definitions for distance that I've seen before include "Full extent of fighting" , "Space between two places" , "Aloofness, reserve" , "A far-off point" , "See 3" .)

I've seen this clue in the Evening Standard.

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