Doctor loves crack (5)
I believe the answer is:
solve
'crack' is the definition.
(I've seen this before)
'doctor loves' is the wordplay.
'doctor' indicates an anagram.
'loves' with letters rearranged gives 'SOLVE'.
(Other definitions for solve that I've seen before include "Crack clues" , "Unscramble" , "Find the solution to puzzle or problem" , "Work out (a problem)" , "Figure out the answer" .)