Not noticing when one's skipping (7)
I believe the answer is:
missing
'skipping' is the definition.
The definition and answer can be both related to thinking as well as being present participle verbs.
Perhaps they are linked in a way I don't understand?
'not noticing when one's' is the wordplay.
I cannot really understand how this works, but
'one's' could be 'is' (Roman numeral) and 'is' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for missing that I've seen before include "Lost without" , "Not to be found" , "Absent with location unknown" .)