Suggestion to leader of expedition — move stealthily (6)
I believe the answer is:
tiptoe
'move stealthily' is the definition.
(I've seen this before)
'suggestion to leader of expedition' is the wordplay.
'suggestion' becomes 'tip' (tip is a kind of suggestion).
'leader of' says to take the initial letters.
The first letter of 'expedition' is 'e'.
'tip'+'to'+'e'='TIPTOE'
(Other definitions for tiptoe that I've seen before include "Creep" , "Go gently" , "Move carefully" , "Walk very quietly, in song through the tulips" , "Walk delicately - musically through the tulips" .)