DNA playing part catching armed robber (6)
I believe the answer is:
bandit
'armed robber' is the definition.
(I've seen this before)
'dna playing part catching' is the wordplay.
'playing' indicates anagramming the letters.
'part' becomes 'bit' (both mean a piece of something).
'catching' indicates putting letters inside.
'dna' with letters rearranged gives 'and'.
'and' going inside 'bit' is 'BANDIT'.
(Other definitions for bandit that I've seen before include "Violent robber" , "Armed robber in the Wild West" , "Armed brigand" , "Outlawed robber" , "(One-armed?) outlaw" .)