Touch upon a stitch with fresh insertion (9)
I believe the answer is:
appertain
'touch' is the definition.
The definition and answer can be both to do with fundamental existence as well as being verbs in their base form.
Perhaps you can see a link between them that I don't see?
'a stitch with fresh insertion' is the wordplay.
'stitch' becomes 'pain' (I've seen this in another clue).
'with' is an insertion indicator.
'fresh insertion' becomes 'pert' (I can't justify this - if you can you should give a lot more credence to this answer).
'pain' placed around 'pert' is 'ppertain'.
'a'+'ppertain'='APPERTAIN'
'upon' is the link.
Can you help me to learn more?
(Other definitions for appertain that I've seen before include "Concern" , "Belong, relate (to)" , "Be relevant to" , "Bear on" .)