Rule may lead to kepi’s redesign as specialist headgear (8)
I believe the answer is:
yarmulke
'specialist headgear' is the definition.
(headwear worn by Orthodox Jewish men)
'rule may lead to kepi's redesign' is the wordplay.
'lead to' suggests taking the first letters.
'redesign' indicates anagramming the letters (I've seen this in other clues).
The first letter of 'kepis' is 'k'.
'rule'+'may'+'k'='rulemayk'
'rulemayk' with letters rearranged gives 'YARMULKE'.
'as' acts as a link.
(Other definitions for yarmulke that I've seen before include "Jewish headgear" , "Skullcap worn by Jewish man" , "A Jewish man's skullcap" , "Jewish skullcap; leaky rum (anag.)" , "A skullcap worn by Jewish men" .)