Novice always has a jemmy (5)
I believe the answer is:
lever
'a jemmy' is the definition.
(I've seen this before)
'novice always' is the wordplay.
'novice' becomes 'l' (as in a learner driver with L-plates on their car).
'always' becomes 'ever' (synonyms).
'l'+'ever'='LEVER'
'has' acts as a link.
(Other definitions for lever that I've seen before include "Rod" , "Bar turning on a fulcrum" , "Means of exerting force" , "Exert pressure" , "Jemmy" .)