Unmarried female writer having time wasted (8)
I believe the answer is:
misspent
'wasted' is the definition.
(thesaurus)
'unmarried female writer having time' is the wordplay.
'unmarried female' becomes 'miss'.
'writer' becomes 'pen' (I've seen this before).
'having' means one lot of letters go next to another.
'time' becomes 't'.
'miss'+'pen'+'t'='MISSPENT'
(Other definitions for misspent that I've seen before include "Passed the time unwisely, as a youth perhaps" , "Wasted (as youth)" , "Dissipated" , "wasted away?" , "Squandered" .)