Urge one lass to get reckless (8)
I believe the answer is:
prodigal
'reckless' is the definition.
(thesaurus)
'urge one lass' is the wordplay.
'urge' becomes 'prod'.
'one' becomes 'i' (Roman numeral).
'lass' becomes 'gal' (I've seen this before).
'prod'+'i'+'gal'='PRODIGAL'
'to get' is the link.
(Other definitions for prodigal that I've seen before include "Wastefully extravagant" , "Wasteful - gold pair (anag)" , "Improvident" , "overspending" , "Extravagant - lavish" .)