Pleated collar (4)
I believe the answer is:
ruff
'pleated collar' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ruff that I've seen before include "Jacobean neckwear" , "High tight collar" , "Starched neck frill" , "Elizabethan or Jacobean neck adornment" , "Starched frill; fish" .)