Regularly found a very short time afterwards, as a rule (2,7)
I believe the answer is:
on average
'as a rule' is the definition.
(I've seen this in another clue)
'regularly found a very short time' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'short' means to remove the last letter.
'time' becomes 'age' (an age is a period of time).
The alternate letters of 'found' are 'on'.
'very' with its last letter removed is 'ver'.
'on'+'a'+'ver'+'age'='ON AVERAGE'
'afterwards' is the link.
I am not very happy about this link. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for on average that I've seen before include "Generally" , "typically speaking" , "Usually" .)