Mock relative after short time (5)
I believe the answer is:
taunt
'mock' is the definition.
(taunting is a kind of mocking)
'relative after short time' is the wordplay.
'relative' becomes 'aunt' (aunt is a kind of relative**).
'after' is a charade indicator (letters next to each other).
'short time' becomes 't' (abbreviation for time).
'aunt' put after 't' is 'TAUNT'.
(Other definitions for taunt that I've seen before include "Jeering remark" , "Make fun of" , "Sarcastic challenge" , "Goad, provoke" , "Mock, jeer" .)