Urge single girl to be reckless (8)
I believe the answer is:
prodigal
'reckless' is the definition.
(thesaurus)
'urge single girl' is the wordplay.
'urge' becomes 'prod'.
'single' becomes 'i' (one).
'girl' becomes 'gal' ('gal' can be a synonym of 'girl').
'prod'+'i'+'gal'='PRODIGAL'
'to be' is the link.
(Other definitions for prodigal that I've seen before include "Wastefully extravagant" , "Profligate" , "Grip load (anag.)" , "overspending" , "Recklessly wasteful or extravagant" .)