Repeat fifth word of radio series (4)
I believe the answer is:
echo
'repeat' is the definition.
(synonyms)
'fifth word of radio series' is the wordplay.
I cannot really understand how this works, but
'of' could be 'o' and 'o' is found in the answer.
The remaining letters 'ech' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for echo that I've seen before include "Repeat or reverberate" , "Sound bouncing back" , "She loved Narcissus - it's recalled" , "Noise heard again" , "from Brussels?" .)