They make slow progress and fall behind others (8)
I believe the answer is:
laggards
'they make slow progress and fall behind others' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for laggards that I've seen before include "Dawdlers" , "Slow people; glad rags (anag.)" , "They tend to fall behind" , "They make slow progress and fall behind others" .)