TV doctor gets a call to stop (4)
I believe the answer is:
whoa
'call to stop' is the definition.
(I've seen this before)
'tv doctor gets a' is the wordplay.
'tv doctor' becomes 'who' (Doctor Who).
'gets' is a charade indicator (letters next to each other).
'who'+'a'='WHOA'
(Other definitions for whoa that I've seen before include "Order (horse) to stop" , "Said to stop a horse" , "Hold your horses!" , "horsy expression?" , "Stop, Dobbin!" .)