Foulness, perhaps, of diesel banned at regular intervals (6)
I believe the answer is:
island
'foulness perhaps' is the definition.
(Foulness is an island in Essex)
'diesel banned at regular intervals' is the wordplay.
'at regular intervals' indicates alternate letters.
'diesel'+'banned'='dieselbanned'
The alternate letters of 'dieselbanned' are 'ISLAND'.
'of' acts as a link.
(Other definitions for island that I've seen before include "Pedestrian refuge" , "Eg, Crete" , "See 13" , "Atoll" , "Barbados, say" .)