Pair of successive lines in verse (7)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
couplet
(Other definitions for couplet that I've seen before include "Two successive lines of verse, usually rhyming" , "Pair of verse lines" , "Pair of lines in poetry" , "bit of poetry" , "Two lines of verse, often rhyming" .)