Scoffs as regatta's jettisoning odd entries (4)
I believe the answer is:
eats
'scoffs' is the definition.
(I've seen this before)
'regatta's jettisoning odd entries' is the wordplay.
'jettisoning odd entries' means one should take alternating letters (letters in odd-numbered positions removed).
The alternating letters of 'regattas' are 'EATS'.
'as' is the link.
(Other definitions for eats that I've seen before include "Seat (anag.)" , "Scoff" , "Comestibles" , "Common grub" , "Food (informal)" .)