Connected ideas — so act in a new way (10)
I believe the answer is:
associated
'connected' is the definition.
('associate' can be a synonym of 'connect')
'ideas so act in a new way' is the wordplay.
'in a new way' indicates anagramming the letters.
'ideas'+'so'+'act'='ideassoact'
'ideassoact' with letters rearranged gives 'ASSOCIATED'.
(Other definitions for associated that I've seen before include "Linked" , "Went about with" , "Connected (with)" , "Made a logical or causal connection" , "in a group, perhaps" .)