Stress bill will need a bit of money added (6)
I believe the answer is:
accent
'stress bill' is the definition.
'accent' can be an answer for 'stress' (accent can mean to emphasise or stress). I'm not sure about the 'bill' bit.
'a bit of money added' is the wordplay.
'a bit of' becomes 'ac' (I can't explain this - if you can you should give a lot more credence to this answer).
'money' becomes 'cent' (eg denomination of dollars).
'added' says to put letters next to each other.
'ac'+'cent'='ACCENT'
'will need' is the link.
(Other definitions for accent that I've seen before include "Mark used to indecate pronunciation" , "A diacritic mark" , "intensity" , "Local way of speaking or enunciation" , "Underline" .)