Stretch former nurse (6)
I believe the answer is:
extend
'stretch' is the definition.
(I know that stretch can be written as extend)
'former nurse' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'nurse' becomes 'tend' (tend can mean to nurse or look after).
'ex'+'tend'='EXTEND'
(Other definitions for extend that I've seen before include "Enlarge, widen" , "Spread - offer" , "Stretch out - enlarge" , "Carry on" , "Straighten out" .)