Change direction by error — endlessly travelling further at regular intervals (7)
I believe the answer is:
reroute
'change direction' is the definition.
(I've seen this before)
'error endlessly travelling further at regular intervals' is the wordplay.
'endlessly' means to remove the last letter.
'travelling' indicates an anagram.
'at regular intervals' indicates alternate letters.
The alternate letters of 'further' are 'ute'.
'error' with its final letter removed is 'erro'.
'erro' anagrammed gives 'rero'.
'rero'+'ute'='REROUTE'
'by' acts as a link.
(Other definitions for reroute that I've seen before include "Send elsewhere" , "Change directions" , "Send on different path" , "Divert" , "Change direction" .)