Pull young lady up: a dawdler! (7)
I believe the answer is:
laggard
'a dawdler' is the definition.
(I know that dawdler can be written as laggard)
'pull young lady up' is the wordplay.
'pull' becomes 'drag' (synonyms).
'young lady' becomes 'gal' (synonyms).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'drag'+'gal'='draggal'
'draggal' back-to-front is 'LAGGARD'.
(Other definitions for laggard that I've seen before include "Dilatory person" , "Dawdler" , "One falling behind" , "Person falling behind" , "Slow mover" .)