A cycle is available (6)

I believe the answer is:

around

'available' is the definition.
(around can mean unoccupied or available)

'a cycle' is the wordplay.
'cycle' becomes 'round' (going round once).
'a'+'round'='AROUND'

'is' acts as a link.

(Other definitions for around that I've seen before include "Present; approximately" , "On every side" , "More or less" , "In the area of" , "On all sides or near" .)

I've seen this clue in The Globe and Mail and The Guardian.

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