To carry on pulling (6)
I believe the answer is:
towage
'pulling' is the definition.
(towage is a kind of pulling)
'to carry on' is the wordplay.
'carry on' becomes 'wage' (I've seen this before).
'to'+'wage'='TOWAGE'
(Other definitions for towage that I've seen before include "Fee for pulling a vehicle" , "Hauling something with a rope" , "Wag toe at the fee for river haulage" , "charge for moving goods" , "pull" .)