I am going to jog memory at the youth centre and ad-lib (9)
I believe the answer is:
impromptu
'ad-lib' is the definition.
(thesaurus)
'i am going to jog memory at the youth centre' is the wordplay.
'i am' becomes 'im'.
'going to' says to put letters next to each other.
'jog memory' becomes 'prompt' (I can't explain this - if you can you should believe this answer much more).
'at' means one lot of letters go next to another.
'centre' indicates the central letters.
The central letter of 'youth' is 'u'.
'im'+'prompt'+'u'='IMPROMPTU'
'and' acts as a link.
Can you help me to learn more?
(Other definitions for impromptu that I've seen before include "unrehearsed piece" , "Spontaneously, off the cuff" , "Off-the-cuff" , "Improvised" , "On the spur of the moment" .)