Furnish egghead with clever remark (5)
I believe the answer is:
equip
'furnish' is the definition.
(equipping is a kind of furnishing)
'egghead with clever remark' is the wordplay.
'egghead' becomes 'e' (head letter of 'egg').
'with' is a charade indicator (letters next to each other).
'clever remark' becomes 'quip' (a quip is a witty comment).
'e'+'quip'='EQUIP'
(Other definitions for equip that I've seen before include "Supply (with items)" , "Fit out, supply" , "Pique (anag.)" , "Give everything needed" , "Provide stuff" .)