17 (7 letter answer) Usual abbreviation for Royal Engineers + N(ew) + what steam engines had attached to store coal minus TEN
18 7 letter word is a stack of tables (also what birds build) around E + 3-letter word for to long (for)
19 7 letter word Abbreviation for Ecstasy + 3-letter word for error, crime or wrongdoing (usually used in religious context) round usual 3-letter abbreviated word for salesman
Hope that gets you moving!