Heading off, get syrup (3)
I believe the answer is:
wig
'syrup' is the definition.
('syrup of fig' is Cockney rhyming slang for 'wig')
'heading off get' is the wordplay.
'heading off' means to remove the first letter.
'get' becomes 'twig' (both can mean to understand or realise).
'twig' with its initial letter taken away is 'WIG'.
(Other definitions for wig that I've seen before include "Disguise for baldness" , "In America it's a toupee" , "False head of hair" , "Artificial hair" , "Artificial head covering, toupee" .)