Straightforward way to achieve financial security (4,6)
I believe the answer is:
easy street
'financial security' is the definition.
(I've seen this in another clue)
'straightforward way' is the wordplay.
'straightforward' becomes 'easy' (easy can mean straightforward or simple).
'way' becomes 'street' (street is a kind of way).
'easy'+'street'='EASY STREET'
'to achieve' is the link.
(Other definitions for easy street that I've seen before include "State of financial security" , "Comfortable situation" , "enjoyed by a roundsman?" , "Financial security -- teeters, say (anag)" , "Situation of financial comfort or security" .)