Dance composed by young woman before work (5)
I believe the answer is:
galop
'dance' is the definition.
(I've seen this before)
'young woman before work' is the wordplay.
'young woman' becomes 'gal' (synonyms).
'before' means one lot of letters go next to another.
'work' becomes 'op' (abbreviation for opus).
'gal'+'op'='GALOP'
'composed by' acts as a link.
(Other definitions for galop that I've seen before include "Couple dance" , "dance music" , "Lively ballroom dance" , "Nineteenth-century dance" .)