What the designer can do stems from investments (6)
I believe the answer is:
invent
'what the designer can do' is the definition.
'stems from investments' is the wordplay.
'from' indicates named letters should be taken away.
'investments' with 'stems' taken away is 'INVENT'.
(Other definitions for invent that I've seen before include "Come up with" , "Devise (something new)" , "Coin" , "Design something new, create by thought" , "Create like Edison" .)