Seek clever incomplete group first (6)
I believe the answer is:
search
'seek' is the definition.
(synonyms)
'clever incomplete group first' is the wordplay.
'clever' becomes 'arch' (I've seen this before).
'incomplete' means to remove the last letter.
'group' becomes 'set' (set is a kind of group).
'first' is a charade indicator (letters next to each other).
'set' with its final letter taken away is 'se'.
'arch' put after 'se' is 'SEARCH'.
(Other definitions for search that I've seen before include "thorough examination" , "Seek carefully (for something)" , "Try to locate" , "Look for something or someone, perhaps chaser" , "Examine closely" .)