Setting in, still without second charge (9)
I believe the answer is:
insertion
'setting' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'still without second charge' is the wordplay.
'still' becomes 'inert' (not moving).
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'second' becomes 's' (common abbreviation).
'charge' becomes 'ion' (an ion is a charged particle).
'inert' placed around 's' is 'insert'.
'insert'+'ion'='INSERTION'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for insertion that I've seen before include "Addition" , "being a word, eg, added" , "Act of putting inside" , "implant" .)