Black cat comes back in a change of direction? (4)
I believe the answer is:
tack
'a change of direction?' is the definition.
(I know that tack is a type of change of course)
'black cat comes back in' is the wordplay.
'in' indicates the answer is hidden within the clue.
'back' says the letters should be written backwards.
'kcat' is hidden in the letters of 'black cat comes'.
'kcat' written backwards gives 'TACK'.
(Other definitions for tack that I've seen before include "Small nail; sail (boat) against the wind" , "Nail - direction (eg of boat)" , "Fix with pins, shoddy material" , "Rubbishy things" , "vulgar" .)