Full stop in Chaucer initially recurring at intervals (8)
I believe the answer is:
periodic
'recurring at intervals' is the definition.
(I've seen this before)
'full stop in chaucer initially' is the wordplay.
'full stop' becomes 'period' ('period' can be a synonym of 'full stop').
'initially' suggests taking the first letters.
The initial letters of 'in chaucer' is 'ic'.
'period'+'ic'='PERIODIC'
(Other definitions for periodic that I've seen before include "Intermittent" , "Cyclical" , "Occasional" , "Recurring at regular intervals" , "Occurring or appearing at intervals" .)