They assist in the formulation of ideas (5)
I believe the answer is:
aides
'they assist in the formulation' is the definition.
The definition suggests an adverb but the answer is not.
'of ideas' is the wordplay.
'of' indicates an anagram (the answer comes from or 'of' the letters).
'ideas' anagrammed gives 'AIDES'.
Can you help me to learn more?
(Other definitions for aides that I've seen before include "Ministerial assistants" , "Military assistants to a senior officers" , "Adjutants" , "Confidential assistants" , "Helpers" .)