Declare — Lara heading off after leg bye (8)
I believe the answer is:
sayonara
'bye' is the definition.
(synonyms)
'declare lara heading off after leg' is the wordplay.
'declare' becomes 'say' (I've seen this before).
'heading off' means to remove the first letter.
'after' says to put letters next to each other.
'leg' becomes 'on' (cricket term, fielding positions).
'lara' with its initial letter removed is 'ara'.
'ara' put after 'on' is 'onara'.
'say'+'onara'='SAYONARA'
(Other definitions for sayonara that I've seen before include "Japanese goodbye" , "Goodbye (Jap.)" , "So long" , "Japanese farewell" , "Japanese valediction" .)