Went on to add "with grass all round" (7)
I believe the answer is:
resumed
'went on' is the definition.
(resuming is a kind of going on)
'add with grass all round' is the wordplay.
'add with' becomes 'sum' (synonyms. I am not sure about the 'with' bit.).
'grass' becomes 'reed' (type of grass plant).
'all round' means one lot of letters goes inside another.
'sum' placed inside 'reed' is 'RESUMED'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for resumed that I've seen before include "Started again where one had left off" , "Once again picked up" , "got to work on again" , "Started again after a break" , "Recommenced" .)