Fibre from old rope (5)
I believe the answer is:
oakum
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fibre from old rope</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for oakum that I've seen before include "Tarred rope" , "Fibrous material from rope" , "Rope fibre for caulking wooden ships" , "Fibre from unravelled old rope" , "Tarred ropes teased out for caulking ships" .)