Joker in a row again (3)
I believe the answer is:
wag
'joker' is the definition.
(I've seen this before)
'in a row again' is the wordplay.
'in' indicates the answer is hidden within the clue.
'WAG' can be found hidden inside 'row again'.
(Other definitions for wag that I've seen before include "Comedian" , "Move from side to side like dog's tail" , "Move briskly to and fro" , "Oscillate - wit" , "Person fond of tricks and playing jokes" .)