A little bit of radio tape-recordings (4)
I believe the answer is:
iota
'a little bit' is the definition.
(I've seen this in another clue)
'of radio tape-recordings' is the wordplay.
'of' says the answer is hidden in the clue.
'IOTA' is hidden in the letters of 'radio tape recordings'.
(Other definitions for iota that I've seen before include "Old letter" , "Greek equivalent of the letter I" , "Tiny or scarcely detectable amount" , "little part" , "Ninthe letter of the Greek alphabet" .)