Information that a doctor is holding back (4)
I believe the answer is:
data
'information that a doctor is holding back' is the definition.
'data' can be an answer for 'information' (data are bits of information). I am not sure about the remainder of the definition.
'information that a doctor is holding back' is the wordplay.
'is holding' says the answer is hidden in the clue.
'back' says the letters should be written in reverse.
'atad' is hidden within 'information that a doctor'.
'atad' back-to-front is 'DATA'.
Can you help me to learn more?
(Other definitions for data that I've seen before include "Information for/from computer" , "Raw facts" , "Facts and statistics collected together" , "Statistical information" , "Facts and figures as processed by computer" .)