US nerd criminal took care of (6)
I believe the answer is:
nursed
'took care of' is the definition.
(I've seen this before)
'us nerd criminal' is the wordplay.
'criminal' indicates anagramming the letters.
'us'+'nerd'='usnerd'
'usnerd' anagrammed gives 'NURSED'.
(Other definitions for nursed that I've seen before include "Carefully treated" , "26dn the ill" , "Cared for the ill" , "Tended to the sick, cared for" , "Tended to while ill" .)