Tick off medical officer in bad Danish (8)
I believe the answer is:
admonish
'tick off' is the definition.
(thesaurus)
'medical officer in bad danish' is the wordplay.
'medical officer' becomes 'MO' (abbreviation).
'in' is an insertion indicator.
'bad' indicates an anagram.
'danish' anagrammed gives 'adnish'.
'mo' going into 'adnish' is 'ADMONISH'.
(Other definitions for admonish that I've seen before include "criticise" , "Rebuke, tick off" , "Warn sternly" , "Caution - reprimand" , "Tell off" .)