Long and limp (4)
I believe the answer is:
lank
'long and limp' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lank that I've seen before include "Lean and limp" , "Spindly" , "Lustreless" , "Long and limp (of hair)" , "Long, thin and often limp" .)