Talk about the old days, about short skirts, clubs, and start of experimentation (9)
I believe the answer is:
reminisce
'talk about the old days' is the definition.
(I've seen this before)
'about short skirts clubs and start of experimentation' is the wordplay.
'about' becomes 're' ('re' means regarding or about).
'short skirts' becomes 'minis' (mini skirts).
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'and' means one lot of letters go next to another.
'start of' suggests taking the first letters.
The initial letter of 'experimentation' is 'e'.
're'+'minis'+'c'+'e'='REMINISCE'
(Other definitions for reminisce that I've seen before include "Indulge in recollection" , "Talk like an oldie" , "Say what one remembers" , "Have fond recollections" , "Recollect past events" .)