Set my clues lacking any regular form (5)
I believe the answer is:
style
'form' is the definition.
(style is a kind of form)
'set my clues lacking any regular' is the wordplay.
'lacking any regular' means one should take alternating letters (letters removed at regular intervals).
'set'+'my'+'clues'='setmyclues'
The alternating letters of 'setmyclues' are 'STYLE'.
(Other definitions for style that I've seen before include "Particular kind, of fashion say" , "name" , "term" , "way of writing" , "approach?" .)