Easily beat theorist's first hunch (5)
I believe the answer is:
thump
'easily beat' is the definition.
'theorist's first hunch' is the wordplay.
'first' indicates taking the first letters.
'hunch' becomes 'hump' ('hump' can be a synonym of 'hunch').
The initial letter of 'theorists' is 't'.
't'+'hump'='THUMP'
(Other definitions for thump that I've seen before include "Common feature of Boxing" , "Hit - defeat heavily" , "clobber" , "Punch" , "Pound" .)