The Knap is the amount of wool (or other synthetic stuff) on a paint roller. Depends on what sort of paint you are using as to which "knap" you choose.Sounds like nap as in sleep.
Hi Peter
It would help if you indicated the clue number and if it was "across" or "down".
ie. 12d) 13a).
Sometimes it makes a difference in the way the clue is written. Other times it may indicate "crossing letters".
Cheers.
Knap does not seem to be right now that I have worked out following "Wear the writer out,crossing river in ancient vessel =trireme .Therefore I now have ?T?P=STEP??
the other one could be fifty fifty (equally) central for school leaver is the 2 L's (fifty) in the middle of the words. But that would mean your L is wrong