Painful effort (7)
I believe the answer is:
travail
'painful effort' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for travail that I've seen before include "Painful or laborious effort, like childbirth" , "Labour, toil" , "Painful labour" , "painful exercise" , "Old word for pangs of childbirth" .)