Lead on runner announced (5)
I believe the answer is:
tease
'lead on' is the definition.
(I've seen this in another clue)
'runner announced' is the wordplay.
'runner' becomes 'tees' (River Tees ).
'announced' indicates a 'sounds like' (homophone) clue.
'tees' sounds like 'TEASE'.
(Other definitions for tease that I've seen before include "Gently make fun of (someone)" , "Torment lightly" , "Playfully make fun of" , "Deride" , "Page of book" .)