Hint to leader of expedition to move stealthily (6)
I believe the answer is:
tiptoe
'move stealthily' is the definition.
(I've seen this before)
'hint to leader of expedition' is the wordplay.
'hint' becomes 'tip' ('tip' can be a synonym of 'hint').
'leader of' suggests taking the first letters.
The initial letter of 'expedition' is 'e'.
'tip'+'to'+'e'='TIPTOE'
'to' acts as a link.
(Other definitions for tiptoe that I've seen before include "Move stealthily, with heels raised" , "Creep" , "Walk stealthily" , "go quietly" , "Lightly pad" .)