Supply base with crack (5)
I believe the answer is:
equip
'supply' is the definition.
(equipping is a kind of supplying)
'base with crack' is the wordplay.
'base' becomes 'e' (I've seen this in other clues).
'with' says to put letters next to each other.
'crack' becomes 'quip' ('quip' can be a synonym of 'crack'**).
'e'+'quip'='EQUIP'
(Other definitions for equip that I've seen before include "Provide with stock" , "Give everything needed" , "Furnish, fit out" , "Provide with suitable gear" , "Arm" .)