Learner in shift working for club (8)
I believe the answer is:
bludgeon
'for club' is the definition.
(both can mean a heavy weapon)
'learner in shift working' is the wordplay.
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'in' means one lot of letters goes inside another.
'shift' becomes 'budge' (synonyms).
'working' becomes 'on' (on can mean working or activated).
'l' put into 'budge' is 'bludge'.
'bludge'+'on'='BLUDGEON'
(Other definitions for bludgeon that I've seen before include "Club used maliciously" , "Bully; heavy weapon" , "Short stick with thickened end as weapon" , "Cudgel" , "Thick stick with a heavy end" .)