Handed a learner a hammer (5)
I believe the answer is:
gavel
'a hammer' is the definition.
('gavel' can be a synonym of 'hammer')
'handed a learner' is the wordplay.
'handed' becomes 'gave' (giving is a kind of handing).
'a learner' becomes 'l' (as in a learner driver with L-plates on their car).
'gave'+'l'='GAVEL'
(Other definitions for gavel that I've seen before include "equipment for auctioneer" , "Mason's hammer" , "Ceremonial mallet" , "Auctioneer's mallet" , "Judge's hammer" .)