In rough sea, might sails be prepared thus? AT?I?
Is the answer to this in Chambers? Only 3 words fit my letter patter and one (ending in P) is a nautical term to do with 'sails' but, other than being totally unable to get to it from the clue, it would also mean I'd have a 5 letter down answer with ?TPE? which isn't in Chambers - Help!