Telling the tale backwards in a telephone call (8)
I believe the answer is:
relating
'telling' is the definition.
(relating is a kind of telling)
'tale backwards in a telephone call' is the wordplay.
'backwards' is a reversal indicator.
'in' means one lot of letters goes inside another.
'a telephone call' becomes 'ring' (I've seen this in another clue).
'tale' in reverse letter order is 'elat'.
'elat' placed into 'ring' is 'RELATING'.
'the' acts as a link.
(Other definitions for relating that I've seen before include "Rendering" , "Connecting things in thought or meaning" , "Telling, narrating" , "account" , "Narrating, recounting" .)