Turn on TV, mostly after current talk (5)
I believe the answer is:
noise
'talk' is the definition.
(I have seen 'Public talk' mean 'noise' so perhaps 'talk' could also mean 'noise')
'turn on tv mostly after current' is the wordplay.
'turn on' becomes 'no' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'tv' becomes 'set' (television set).
'mostly' means to remove the last letter (most but not all of the word).
'after' is a charade indicator (letters next to each other).
'current' becomes 'I' (symbol for electric current).
'set' with its final letter taken off is 'se'.
'se' put after 'i' is 'ise'.
'no'+'ise'='NOISE'
Can you help me to learn more?
(Other definitions for noise that I've seen before include "Unwanted sound" , "Hum" , "Uproar" , "interference" , "Racket, din" .)