One up around front of Argos could be a looter (6)
I believe the answer is:
raider
'a looter' is the definition.
('raider' can be a synonym of 'looter')
'one up around front of argos' is the wordplay.
'one up' becomes 'rider' (I've seen this before).
'around' indicates putting letters inside.
'front of' suggests taking the first letters.
The first letter of 'argos' is 'a'.
'rider' enclosing 'a' is 'RAIDER'.
'could be' acts as a link.
(Other definitions for raider that I've seen before include "Surprise attacker" , "One who makes a sudden swift attack" , "Depredator" , "One plundering" , "One who makes surprise attack, perhaps to steal" .)